Occasional work as a “guinea-pig” has some strong plus-points. It is unskilled, often fun, pays well and helps others - furthering medicine, for example, or enabling retailers to improve customer service. Here Times Money rounds up the options.

Clinical trials

Phase 1 trials of new medicines offer opportunities for healthy participants to make hundreds or thousands of pounds in a few days. However, they represent the first time a drug is tested on humans and come with the risk of side-effects, from nausea to death. The Association of the British Pharmaceutical Industry (ABPI) puts the incidence of “serious adverse events” at about 0.02 per cent - one in 5,000.

Most trials are run by private companies and involve a short stay at a special facility. The unit in Manchester run by Icon, the clinical researcher, offers pool tables, video games, DVDs and newspapers, plus a quiet area with internet access. The company's website states: “The hard work is carried out by our professional medical team, which leaves you free to relax and enjoy the facilities.”

Malcolm Boyce, of HMR, a contract research organisation that conducts trials in London, says that participants can often “sit back” but sometimes undergo cognitive tests or more invasive procedures - swallowing an electroid camera, for instance. “I have volunteered in about 100 trials without a side-effect,” he adds. “The most common discomfort is a headache from caffeine withdrawal.”

Non-residential trials are sometimes conducted. Icon, for example, is paying £1,038 to right-handed males aged 18 to 40 to take part in a trial on the pain-killing effects of Botox, which involves two outpatient visits.

Details of forthcoming trials can be found at EnterTrials.co.uk, a portal website, or at the sites of the trial companies (see box, facing page). Men aged 18 to 45 and of regular weight are most in demand.

Payment is about £100 to £300 a day, often with travel expenses on top. Under ABPI guidelines, the sum should factor in time, inconvenience and discomfort, but not risk. So a £1,000 three-day trial is not necessarily less safe than a £600 trial over the same period. Trials include a check-up that would cost hundreds of pounds in the private sector.

Should a participant be injured in a trial - sustaining lasting damage, rather than immediate discomfort - he or she is compensated in line with court payouts for equivalent injuries. The Association of British Insurers says that involvement in trials should not affect life or health cover.

Richard Ley, of the ABPI, emphasises that trials are run on the principal of informed consent. Companies must provide jargon-free information on processes and risks in advance, and participants can drop out at any time (receiving a fee). “If you do not understand a trial, don't do it,” he adds.

The British Medical Association has information on the regulation of clinical trials at BMA.org.uk. The framework has been tightened since six volunteers suffered simultaneous multiple organ failure at the research unit at Northwick Park Hospital, northwest London, in 2006.

Dental treatment

Trials of dental treatments tend to be unpaid but can provide free procedures, such as crowns and implants. For example, the Eastman Clinical Investigation Centre at University College Hospital, London, is recruiting healthy volunteers who need a single tooth to be replaced by an implant. This procedure is not available on the NHS and would cost £2,000-plus if performed privately.

The British Dental Health Foundation says that there are also opportunities for free treatment by dental students at all UK dental schools. The British Dental Health Foundation has a list of the schools at www.bda.org.

Paid to shop

Market research can involve being paid to buy clothes or go to the pub. For instance, Retail Eyes, a research agency, sends its 179,000 members on up to 16,000 “mystery shopper” assignments a month. Members use a shop or service and then report on the quality of the experience.

Simon Boydell, of Retail Eyes, says that payment varies, but members - who register free - earn about £6 to £10 per task, plus expenses, and are reimbursed for, and can keep, any purchases. The agency's clients include the JD Wetherspoon chain of pubs, JD Sports and WH Smith. “Non-shopping tasks might be nights in hotels or trips to the bookies,” he adds.

While most assignments are straightforward, some involve acting out a scenario. For example, a mystery shopper might be required to ask questions or make a difficult request.

More information on mystery shopping is online at RetailEyes.co.uk. Applicants complete a form detailing their interests and then access details of suitable assignments by e-mail and at the site. Mr Boydell says that most tasks are snapped up within minutes and many take place at lunch times, evenings and weekends, so are compatible with a full-time job.

Retail Eyes is also one of a number of companies to run focus groups. Participants are recruited from its mystery shoppers and are paid about £40 to £60 to join a group discussion on a product or service. Another company offering focus groups is the Campden Chorleywood Food Research Association, at www.campden.co.uk, which pays panel members £5 to £50 for their opinions on food and drink products in group chats or online surveys.

A free haircut

Most hairdressing academies offer free haircuts and other services by students. Louise White, editor of Hair magazine, says: “They are crying out for volunteers. The students are supervised so it's pretty safe and can save big money.”

Box: Your opinions really are valued online

Online surveys enable internet users to trade their opinions for cash from the comfort of home. Signing up with several survey sites can net the keenest respondents hundreds of pounds a year.

Most such surveys feature multiple-choice questions on brands and consumer goods and take about 15 to 20 minutes to complete. Respondents are usually paid between £1 and £10.

Among the most popular survey websites is CiaoSurveys.com. Members register free and are sent two to three surveys a month on products that match their profile, from cosmetics and breakfast cerals to white goods, pet food and holidays. More quirky tasks include rating possible designs for book and DVD covers. A spokesman for the company says that members can expect to make about £2 to £3 a month, adding that most are motivated more by improving the brands they like than by money.

Members can supplement their survey income by reviewing consumer goods at Ciao.co.uk. The site pays between 0.5p and 2p each time a reader clicks to say that a review has been helpful.

An alternative site to consider is itsyourview.com, run by several market research companies under the slogan “earn £1 for every five minutes of your time”. It sends members about two or three

surveys a month. Meanwhile, Valuedopinions.co.uk pays between £1 and £2 per survey in gift vouchers or donations to charities, including the Red Cross and the World Wildlife Fund.

For more cerebral surveys, you can join the panel at YouGov.com to share your opinion on anything from politics to painkillers and pensions. Members receive about 50p to £1 per survey, but some are “prize draw” surveys where one participant receives a bigger cash prize.

YouGov surveys have a high media profile and the website hosts regular commentary articles by the broadcaster John Humphrys. One downside is that members must clock up at least £50 in earnings before claiming payment, against £5 with Ciao.

All the survey companies expect honest and considered answers. Their software identifies members who tick boxes at random to turn a fast buck.

Searching the web for “paid surveys” brings up a huge number of hits, many of them useless pages of old links. Note that genuine market research companies do not charge people to participate in surveys.

Case Study: Paid to eat, drink and shop

Kelly Hunt discovered mystery shopping when she picked up a leaflet for Retail Eyes at her university campus. The 19-year-old student, of Milton Keynes, says that she liked the idea of “extra cash and free drinks”.

She adds: “Registering online was free and straightforward. I log on to the site quite often to check what tasks are available. You have to be quick to get the best ones.

“I have been paid to shop, to drink at Wetherspoons pubs and to eat at nice restaurants - you can take a friend and have three courses.

“When you log on to the Retail Eyes website you see a list of tasks in your area, but you can also run a search for tasks elsewhere, which is useful if you are visiting someone.”

Ms Hunt says that completing the online feedback forms is easy and that many of the questions are multiple-choice.

She adds: “I have recommended mystery shopping to several friends and to my mum. Because she has a different profile, as far as companies are concerned, she gets different offers - more meals out, say.

“Overall, it's great fun. The important thing to remember is to hang on to your receipts.”

Clinical trials links

Roche: Welwyn Garden City, www.RocheUK.com.

Quintiles: Guy's Hospital, London, www.AreYouTheAnswer.com.

HMR: Central Middlesex Hospital, London, www.hmrlondon.com.

Parexel: Northwick Park Hospital, London, www.drugtrial.co.uk.

AstraZeneca:Nottingham and South Manchester, www.healthyvolunteers.com.

Icon: Manchester, www.iconvolunteer.com.

Veeda: Plymouth, www.nowvolunteer.co.uk.

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