My friend had my last betta for the last week of break and he died in her care.
I missed having a fish so I went to the local pet store (where bettas are kept in real tanks and get water changes, even) and picked out a lively looking crown tail.
I have him in the same set up I did for my last betta: ~3 gallon tank (it's a penn-plax starter kit), hydor mini heater, a penn-plax filter (came with tank and has helpful background noise), long flowing soft plastic pants (my last fish would sleep/rest in them), short plants (which are mostly good for a hiding wall), and a treasure chest.
He was pretty agitated at first, but seems to have settled down. It was quite entertaining to watch him approach the toy treasure chest and swim off.
Here is my tank: http://smg.photobucket.com/albums/v6...rrent=Fish.jpg