See this Firefox extension: http://pasteandgo2.mozdev.org/
It allows you to send the latest thing copied in the clipboard (both types, on Linux) to the URL bar, very nice for unlinked URLs, but also to make Google searches on any random word (I've disabled the "lucky" part).
It is however a bit annoying to have to switch to, or even start Firefox to do this. Also, some people like other browsers...
So, an idea for a plugin to Glipper: Paste and Go with shortcut and possibly menu entry, that sends the clipboard to the systems default browser, which would make it work from any application.