ClipToWebCM is a contextual menu plug-in which tries to open the currently selected text (or clipboard contents if there is no selection) as a URL in your default web browser.
Of course this isn't anything a copy and paste operation can't achieve, but it's quicker. It's also more versatile than the "Open URL" contextual menu item since it doesn't require a full URL. (Note: As of version 1.0.2 the selection can also be a Finder file or folder; the text will be the name of the object.)
As of version 1.0.2 you can use the provided system preference pane to create a list of extensions that the contextual menu will use to build alternate forms of the URL, one URL for each of the extensions, if the selection does not already have an extension:
The resulting contextual menu: