If you want to deal with only one exchange for your alt-currency needs (DVC,LTC,PPC,SC,IXC,NMC) then there is only one option:
https://vircurex.comI agree, but they've lately started dropping some of the alt chains, one by one
Still the best tho.
I hope it doesn't evolved like allchains.info did, slowly reducing and reducing until it's back to bare bones...
PS: is Bitparking's PPCoin exchange down ATM?