These are some simple but very useful fraction diagrams.
Update: Now in red, green, blue, amber, cyan, orange and yellow and organized by denominator.
Another Update: Now includes division diagrams.
If you like my massive sets of diagrams and need something new, let me know. It's probably something I'd like to make anyway.
Mathematica 6.0 code for generating these images (requires Mathematica) included.
For commercial use or for showing appreciation. For classroom use, see the free version.