Odd name for a thread but it really is what this comes down to. I have two male Betta Splendens. One lives in a 10 gallon by himself, and the other lives in a 80 gallon with community fish.
I thought I would share and contrast two ways I keep my bettas for others to see. Some people may consider this a waste of space for a single fish:

but in my mind this is perfect. When the plants grow in and I can fix this tank up with a nice piece of wood and some additional plants this will become a beautiful little under water garden complete with one completely happy little Betta. To me...that is happiness unto itself as a fish keeper.
The tank itself was cheap, and I am running nothing more than a heater and an air stone to keep the water moving at the top so things don't go stagnant. The plants will take care of what little the fish puts out. In fact it will be necessary to dose this tank with a wee bit of fertilizer to keep the plants happy.
Now my other betta, his name is Blue Gill. He started out in a 5 gallon tank.
Later on he upgraded to a 20 gallon and for two months that thing grew out into a beautiful underwater paradise where learned to get a long with a school of Harlequin Rasbora.
Now he lives in an 80 gallon tank with his previous tank mates, a Peacock Eel, and 8 very silly loaches.
This is just one section of that tank:
I am really proud of Blue-Gill. He's come a long way after 8 months and has been a very tolerant trooper the entire time. He also battled through a time of sickness when the 80 gallon first got set up.

This is his second bubble nest in the 80 gallon.
Here you can see see video contrast of both fish and tanks:
http://youtu.be/WEIYZQyEF_4