Your block erupters will only work for SHA256, that means you are limited to some of these cryptos: (or more)
PPCoin (I like this sha256 alt, and their dev is super awesome)
Terracoin
Freicoin
IXCoin [merged*]
Devcoin [merged*]
NameCoin [merged*]

*Merged to bitcoin blockchain, you can mine them in addition to bitcoins.
(it's like getting a few % profitability extra, free)