I've been working on a little kite physics demo app:
After chatting with Allistar at the £5app about how he did physics simulations I was pointed at "Gauss-Seidel" as an easy way to handle constraints. This led me to Advanced Character Physics by Thomas Jakobsen, which explained it all very nicely. That coupled with some info from NASA on forces on a kite helped me create this simple 2D "simulation".
It's not yet finished, but I thought I'd share some of my progress. I want to turn it into a slightly more rounded demo or perhaps even a simple game of some sort, with some scenery etc. I'm quite happy with how it's turned out so far - even though I did waste a fair bit of time getting drop-shadows working...
It's all written in Java, so it'll be nice and easy to put online later. I think I'll probably release the source too, as the physics and constraints code is fairly generalized. In fact through the use of generics and a few other tricks the code is setup to allow (potential) re-use for 3D physics too.