Second Life texture calculator
The build tools in SL provide all that's needed to place arbitrary sections of texture on any given face of a model.
However, the interface to do that is frustrating, as it requires the user to caculate texture repititions and offsets.
I created a tool (using Python and the Pygame library) to make that a lot easier- the user need only load a texture and then click-drag to select a rectangular region. The texutre repititions/offset values are calculated automatically.
The tool also allows the highlight color, and the color of the guide lines to be changed for maximum contrast with a given texture. Go here for a video demo.