You may be out of warranty anyway, if so ROMs can help stave off the boredom. Just make Titanium Backup your first download
Look into CM7 or MIUI, and a few others like Sensei Mod are listed in some threads. Searching for screenshots can help you decide.
Also consider what you're doing with the phone afterwards. I intend to keep mine as a 4.3" tablet once I upgrade, but if you plan to sell I would place a higher value on a never-rooted, pure stock phone. Others are looking for pre-rooted, so check out your favorite sales channel to see if there's a price delta.