Yahoo! is the latest internet company to allow users to “roll their own” search engines and create tools that aim to cut through the explosion of digital dross on the web.

A new test search site, Yahoo! Alpha, taps a range of sources, including Flickr, the online image database, Wikipedia, the non-profit encyclopaedia, and YouTube, the video-sharing platform that is owned by Google, Yahoo!'s arch rival.

In a departure from traditional “one-size-fits-all” search engines, users can customise Alpha to try to sidestep irrelevant answers – by giving, for example, prominence to video results. Users can also link the tool to specialist outside search engines that only look at certain, trusted sites.

The latest in a new generation of bespoke search tools, Alpha's "personalisation elements" are being seen as signalling a shift in the industry.

Search accounted for 60 per cent of online advertising spending in the UK last year, according to the Internet Advertising Bureau, with £1.2 billion spent. Google, the runaway leader, accounted for 75 per cent of that sum.

However, search revenues are slowing, and industry executives are concerned that users are facing growing volumes of irrelevant results. There are also fears over potentially untrustworthy sites, which can be used by hackers to obtain personal information such as bank details.

In response, Google last year launched Co-Op, a “free custom search engine that reflects your knowledge and interests”. It allows users to specify the websites that they want to search and to integrate the search box and results into their own websites.

Rollyo, a Silicon Valley start-up, has garnered attention on the web by offering a service that allows users to “roll their own search engines” by listing up to 25 sites they are interested in.

Google has also built Searchmash.com, which gathers together web pages, photos, videos, blogs and Wikipedia entries, and asks its users for feedback on the relevance of results.

Microsoft, which has languished in search despite being the world’s largest software company, is also making the area its “number-one priority”, company insiders say. It is investing heavily in Windows Live, another online platform that can be customised by users.

Systems that deliver "personalised localised results" are being developed for searches carried out on mobile phones. Google, Yahoo! and Microsoft have all recently announced deals with handset makers and service providers, to have their applications pre-installed on handsets.

Last week, Google unveiled a service that uses speech recognition to allow users to ask for local information over their mobile.

The internet giants are terrified about being wrong-footed in a rapidly-shifting market. As they jockey for position, their search engineers are being asked to dream-up “what users don’t yet know they need”.

Alpha emerged from Yahoo’s “Hack Day” programme, a scheme where the company’s engineers are given a day off from their usual duties to “sit down together and innovate”.

Brett Poole, of the Australia-based Yahoo!7 Search Team, which developed the site, said the idea was “born out of pizza and furious coding”.

He added on his blog: “While aggregating feeds on one page is nothing new, we wanted to take a federated search concept one step further. With this beta, we have introduced personalisation elements that not only allow users to customise their view, but also to add their favourite search service.”

The site also allows users to share their customised settings with each other.

“We thought the idea was good enough to develop further into a public beta site and get a few ideas from the Australian search community at large,” Mr Poole added.

Rick Broida, of the Lifehacker blog, said that Alpha has “the slow, buggy performance” to be expected from a test site, but added: “But see if you don't come away thinking this is the way search engines oughta be.”

Yahoo! has some serious catching up to do as Google dominates search. In the UK, in terms of “click through” numbers, Google accounts for nearly 70 per cent of the market, according to NetRatings, the market researchers. Yahoo! comes way behind, in second, with just 9 per cent.

According to a recent test carried out by Information World Review, Google also holds the edge in terms of the relevancy of its search engine’s results, scoring 70 marks out of a possible 100, compared with 68 for Yahoo!.

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