You mean the thumbs up symbol you choose for the thread? If so, I believe Shelly made those, and Shelly has not been around much.
Here's an older version of the editor buttons Shelley put together: Editor Icons - vBulletin.org Forum But, the ones that are being used here (and AdminExtra) are different than that. I was going to ask about these as well. Anyone know where the 'updated' ones are located?