6:14 PM
Well, after a lot of good suggestions, multiple installations, and a fair share of playing around, I have found my new search tool: Dave's QuickSearch Deskbar is everything I was looking for and so much more that I barely know where to begin.

Start with a search interface that can not only reach out to Google and Dictionary.com as I hoped, but also more than 200 other sources. Throw in a multitude of tools including an alarm clock, a calculator, a calendar, currency converters, password generators, an email handler. Make it amazingly (and relatively easily) customizable. As icing on the cake, make it open source freeware and give it a community of folks adding new functionality all the time. That's DQSD. I can even think of a few searches I might try writing myself, if I can wade through the Javascript--though I might not need to.

It may have a slightly arcane syntax that takes a bit of getting used to, but it makes up for it with an easily accessible and terrifically useful help system. I've only had it installed for four days and I've already added it to the package of software that will get installed on any machine I use. I give it my heartiest recommendation.