There really isn't much development happening anywhere else, you have Bitcoin and NXT.
wut
Well there's Bitcoin, (a ton of copies and renditions of bitcoin with different names ripped of from the same source code), and NXT. The reason NXT is having so much success now with additional development is because they had the resources to develop a coin from scratch in the first place.
There are rumors about other coins being written (like NEM) but at the moment there aren't any.
Let's see.. there is Ethereum in the works, Bytecoin was coded from scratch, Zerocash (may or may not use bitcoin code) coming soon, etc. Bitcoin and NXT are not the only ones.