Just added another really handy shortcut to OmniWeb 5. With it, I can just hit "command+L" to get to the address bar, and enter "del xml database" and del.icio.us will spit out all bookmarks matching the words (after del, of course - in this case I'd get all bookmarks tagged with XML database)
So insanely simple, yet amazingly useful. I have similar shortcuts set up to hit the Wikipedia, and some of the mailing list archives that I use, oh yeah, and Flickr tags, too! Pretty handy stuff. Thanks Omni! (I'm sure this stuff could be trivially adapted for use in Firefox or somesuch, too...)