My personal favorite: Google Co-op. Among other things, it gives you the ability to become Google — that is, to set up customized search results that your colleagues can then subscribe to. Say you're a biologist with a database of species information. You can set up a Co-op trigger where the keywords are species names, and tell your colleagues to subscribe to it. Then when one of them does a regular Google search where the search string includes a particular species name, your database's results for that species will come up in, say, a special one-box above or off to the side.

Now if only Google would decide whether it's "Coop" or "Co-op". The URL is http://www.google.com/coop/, but on that page it's always referred to as "Co-op", with a hyphen. But if you go to the corresponding URL:

http://www.google.com/co-op/

...you get a 404 Not Found error: "The requested URL /co-op/ was not found on this server." (At least, this is true as of today's date.)

Know anyone in a position to fix that? :-)