Some of the major search engines release beta versions of their products with different interfaces, features or focus for people to test & give them feedback on. Take a look at what may or may not be coming up in the next few months.

Yahoo! Mindset
Uses machine learning technology to give you a choice: View Yahoo! Search results sorted according to whether they are more commercial or more informational (i.e., from academic, non-commercial, or research-oriented sources). Handy, for example, when you are looking for book reviews rather than ads selling the book.

Yahoo! Instant Search
Puts the top match on the search screen while you are still typing in your search terms. Doesn't work for all searches, but you can click on a button to perform the search. They are surveying whether users want it added to the Yahoo! Search page.

My Web 2.0
Yahoo!'s social search engine which complements web search by enabling users to search the knowledge and expertise of their friends and community in addition to the web. It is powered by Yahoo!'s MyRank Search Technology, which provides personalized search results based on the shared knowledge of the people they trust.

Live Search Virtual Earth
MSN's version of Google Earth, with a 2-D & a 3-D version. With free registration it allows you to save maps to a scratch pad. Microsoft's Terraserver also provides maps, including topographical ones.

Google Code Search
Search public programming code, similar to Koders but with an advanced search mode option.

Google Experiemental
Several experimental interface features, including "Timeline & map views, which displays results on a timeline or map, and two interfaces which allow you to search deeper in a particular type of content or to search related items.