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.
So Ethereum is meant to be a turing complete language for bitcoin transactions. It
will be new code when it's deployed but isn't it meant as more structure built on top of Bitcoin?
Bytecoin? Bytecoin is self described as:
The goal of BTE is to make a Bitcoin clone 1:1 copy. Giving people a real option to the rising difficulties of other coins while maintaining all the things that made Bitcoin so successful.
on their own page. It is their one sentence summary of their coin!