I haven't been getting nightly builds recently and I just did so when I noticed at The Burning Edge that 2004-04-11 builds include this new "Add keyword for this search" feature. Now that is so useful because the old way of doing this is so non-intuitive and difficult to explain to non-technical users (who really wants to do the "%s" thing other than people like us?).
I went in to Bonsai to check out the CVS checkins to the code and Ben Goodger had this CVS comment:
provide a convenient way for adding smart keywords for web page searches by adding a context menu to form fields with HTTP-GET form actions.
So it works only on GET form fields - I was wondering why it didn't work for just any textbox. This was checked in on 2004-04-09, so I may be a little behind, but it is too good a feature not to talk about. UI improvements are so crucial and so much more important to naive users (naive in the nice sense of the word) because all they ever think of Firefox is the interface. More please, and thank you!