When I began stitching I wanted a way to visualise bags before i made them, and a way to try out new patterns and colour combinations.
I then discovered a soccerball model in the built in components library of google sketch up. With a few adjustments to the pent hex ratio it was looking like a hard footbag and I have found it really really useful in trying out colours, looking at new patterns, especially spiral which i created in sketchUp then simply followed the picture on the screen as I was stitching, rotating etc when needed.
I have also used it for dimensions. As it is all done to scale and gives dimensions you can scale the model to the diameter you want then the pent lengths (which would be after gather) and short hex lengths are given so you can find what sort of length you should look for for whatever size bag (more useful for beginners)
Anyway I have definitely found this to be a useful tool. It can be found here:
http://sketchup.google.com
Here are some screen shots:




If anyone downloads it and wants the basic model I made with a better hex pent ratio or the 8/12 blur, rainbow, atomic, stripy, bipolar or spiral patterns I've made then give me a PM.
Hope this can help some new kids on the block (there seems to be loads at the minute)
Matt