Don't forget to visit Ninerpedia; our wiki about the TI-99/4A. Check here.
If you are the owner of one of the programs or sites and do not want it posted, please let me know and it will be removed immediately.
Also if you think a reference to an important development resource is missing, then please let me know and I'll be happy to add to the list.
If you are new to the TI-99/4A or returning after a long time, then you might want to check out the TI-FAQ page here.