I've been working on the Student Line Grapher a lot lately and was doing some research to make sure that no one else had already created the same thing and I found this interesting program C.a.R - Compass and Rule. I believe that the audience is slightly different and the learning curve for C.a.R is harder than the Student Line Grapher but C.a.R also has a lot more features. C.a.R. is dynamic geometry program. Basically, it simulates compass and ruler constructions on a computer. But on a computer, much more is possible. Check out the website for more details n what it can do. Since it is Java based you can even integrate it into your website or you can run it on your local computer.