I would recommend the whole assortment of gaming console emulators. I have seen them running gorgeously and... well, let's face it, the phone was made for them.
If you have root, Root Explorer and Titanium Backup are quite the asset, and if CWM comes to the phone, ROM Manager will be an important tool as well. 3G Watchdog if you have a cap on your data connection. My other recommendations are more sectorial: Cool Reader for ebooks, Dropbox, Firefox and GPS Aids.
Spanish site for Tizen, Ubuntu Touch, Firefox OS, and other free mobile OS.