TV-MA is United States television's answer to the MPAA's R rating. Why it wasn't just called TV-R is beyond me. Anyway, here's some of the TV-MA stuff on TV:

• virtually nothing on broadcast TV, thanks to FCC rules prohibiting "shit, piss, fuck, cunt, cocksucker, motherfucker, and tits" (George Carlin) from being broadcast over FCC-owned airwaves
• Comedy Central's South Park
• HBO's The Sopranos and several other original series
• /msg me if you know of more