This stat has changed several hands today as it made its way up the meme chain, but according to Tomi Ahonen, via Open Gardens, SMS brought in $75 billion worldwide in 2005. Tomi says:

To put it in context, Hollywood box office is a bit below 30 B USD. Global music industry revenues are about 35B. Videogaming, consoles and all software are about 40. And the total value of all laptop computers sold in 2005 was about 65 B USD. SMS alone earns more than any of those industries.... And SMS is still over 90% profit.

Applications like SMS come along probably only once in an industry. Mobile TV, mobile music, none of these will provide the sort of simplicity, ease of use, "virality" or margins that SMS does. Anyone have suggestions for the next such application, if at all?