Service Scrubber 1.1.5
One of the most underestimated features of Mac OS X is the services menu, which lets you perform actions on the current selection, regardless of the application you're currently working in.
These actions include opening a URL in your browser, sending a snippet via mail, having text read to you, and so forth.
Unfortunately, all kinds of applications add their own entries to the services menu, making that menu grow incessantly. For most users, it has in fact grown beyond the point of usability a long time ago. And we haven't even addressed keyboard shortcut issues here.
Mac OS X 10.4 or higher.