Status
tgeg is still under development. There is a fairly complete DOS version available for download which is very good at graphing functions and conic sections. A Windows/Linux version is available, but it has a long way to go before it will be especially useful.
If you are passionate about mathematics and think that teaching a computer how to do simple algebra is a fun way to spend a Saturday afternoon, please contact me or leave a message in the forums. Even if you are not a developer and don't want to be one, it would help just to have someone I can bounce ideas off of.