Only just spotted this thread. Been fascinated by the whole thing.
I've invested just a small amount in some Peercoin (http://peercoin.net/). Mainly for a little bit of fun more than anything.
Reading up on it there seems to be opinion that it's coded in a more long-term, sustainable method than Bitcoin. That could of course be biased opinion. Cheap enough for me to have a pop and let it sit and see what happens.
Bitcoin is entirely sustainable, thats why its worth billions.
All the new coins coming along offer nothing of any real benefit IME, satoshi did a decent enough job in the first place.