Sin City 2 (Electric Boogaloo!) and 3 (not in 3D)

[yendi]

Robert Rodriguez will be shooting back to back sequels for SIN CITY 2 and 3 starting February of next year for a release presumably summer of 2007.

(link ganked from sweinberg)

Also mentioned is the fact that Double-R will be helming the long-rumored new Conan movie.