Projects on display during a Microsoft Research event yesterday included a method for personalizing Web search results based on the contents of the files on an individual user's computer hard drive.

The project reflects a broader push in the industry to improve the relevance of Web search results by tailoring them to the person doing the searching. But other programs, including Google's personalized search engine, have approached the challenge by having users create profiles to define their preferences.

http://seattlepi.nwsource.com/business/214288_techfest03.html
via Greg Linden

If I wanted to improve personalized search I'd use the user's email (either GMail, Hotmail or Yahoo Mail) to discover their interests. I'd use any organisation the user has done using their mail folders to cluster the search results and I'd use their contact lists to highligh results from people they know.

Ask.com (who I'd give the prize for “second best search engine after Google” to) don't have an email offering so they couldn't compete in that way. They do, however have Bloglines which would allow significant personalization. Yahoo (with MyYahoo) and MSN (with something – is it called MyMSN?) both have blog readers integrated which would allow discovery of the users interest as well.

If I were building a new search engine and I wanted to compete on the basis of personalized search the first thing I'd do is make it easy to subscribe to search results. A search subscription is a great indicator of interest! Unfortunately there are some technical difficulties involved in identifying who is subscribed to which search (most client-side aggregators don't share cookies with browsers) but there are ways around this (unique URLs for each subscription, and only logged in users can create subscriptions).

PubSub.com is currently the closest thing around to an ultimate database of users search preferences, though.