I hadn’t done any monkeying around with Greasemonkey for a while until the other day when I came up with this script: http://github.com/ianoxley/open-selected-links

Any links that are present in the selected text will be opened on the mouseup event, except for the Cached and Similar links you get in Google search results.

If you’ve got and suggestions for improvements, let me know in the comments :)

UPDATE

The script has been updated so that you now have to press the Ctrl or Cmd key while selecting the text, in the same way that you would Ctrl / Cmd + click to open a link in a new tab.