Full Tilt and Bugsy's Club both do razz for real money. They also do HORSE tourneys (including STTS), although FTP has so many more players, you can find a HORSE game more quickly there.
And FTP have started doing satellites to the $50k WSOP HORSE game... for those with larger bankrolls

Irish - is that the same as Crazy Pineapple? (I.e. like Hold'Em but with three cards and you discard one of the three on the flop?) If so, Ultimate Bet is the only place for that.
Lowball - I don't know of anywhere that does single draw lowball, but the Triple Draw variants (ace-to-five and deuce to seven) are available on Ultimate Bet - cash games only.
The Tribeca Network does Badugi/Padooki, which can best be described as being
sort of like a four-card version of Triple Draw Lowball, but with a few
key differences - most of the big Tribeca sites have the rules and some basic strategy for that one on their homepages.