Tenebrix and GeistGeld supposedly premined 8 million? I am still trying to figure out if these are one big troll currenies. Iocoin, was a get back at ixcoin. Tenebrix did make a client, so he might just be having fun, but has no details on the amount that will be made.
So there might only be
Namecoin is stable enough (as well as bitcoin) to be not considered. I consider the only true competitors to IxCoin (which I fully support, by the way) the larger SolidCoid (which isn't even up right now), and the smaller GeistGeld and Tenebrix. I0Coin is dying, and the bid side has dried up. Although GeistGeld and Tenebrix both have the weakness of being able to lose all their value in a blink, so I am not currently speculating there. My economic positions are:
SolidCoin: LONG (currently closed)
(too bad there isn't a easy way to short I0Coin, since that would involve taking a loan)