Thats awesome, Thanks. There should be a complete list so ppl can make their own
Unfortunately, the list of altcoins is ridiculously large by now, and I don't think it would behoove (one just doesn't get to use that word very often) anyone to list them all given that the vast majority of them are no longer being developed or supported. A limited number of altcoins - the most popular and actively developed ones - might be good to list, with notes on how to find the prefix for any other altcoin.
Note that some altcoins
may have further restrictions on alphabet allowed, i.e. if they don't implement the same Base58Check, in which case they'd be moot as far as generating vanity addresses goes..at least without modifications to the vanitygen client.
( The utility in this thread is just a batch file front-end - which itself hasn't been updated since July 2014. )