I just finished my first (of what I'm sure will be many) script for the freeware Big Cat contextual menu plugin. Big Cat allows you to write scripts to handle files or highlighted text in any application that supports system-wide contextual menus.
WebSearches allows you to search for your highlighted text on one of several web sites. The part I love the most, though, is that the user can ADD their own searches to it, simply by running a search on the site they want and looking at the URL of the results page. Most searches use the GET method, and thus you can see the whole search right in the URL. Once you have that, you can add your search to WebSearches' list. Check it out.