libNoise generates coherent noise. Map Maker is similar, but uses a diamond square algorithm. It has not been rigorously tested, but most things that don't involve file reading/writing should work. I really only changed the makefile.
The libNoise demo program creates terrain using perlian noise, and renders it using noise utils. Noise utils is not part of the library. The source is included in the library download. Nunchuk c + analog stick changes lighting. Wii remote A generates a new random landscape.