There are plenty more tribes. I've used SteemLeo, which is where people go to talk business and investments. SteemAce is for gaming content. I think if you use the SteemPeak frontend, you can actually see all of the tribes there with a push of a button or two.

A lot of use received air drops early on. You actually have 1000 CCC tokens sitting in your Creative Coin wallet. If you stake them, you'll be the 2165^th account to do so, and your vote becomes that much more powerful, when voting for content with the 'creativecoin' tag. You might even have some Palcoin, I'm not sure, but that Steem Engine link I gave you has it all in once place.