I found a cool project...I'm about halfway done with it, as in, I've got the receive side working but haven't built the PTT/xmit data part yet...The program is called Direwolf and the particulars and downloads are
here...Once I get Direwolf transmitting and digipeating, I'm gonna try to write a little terminal program and see if I can interface with it...If I can do that, we should be able to use the guts of the terminal program to pass APRS data and pretty much anything else we want through it...If you want to play with it, I have some notes of some of the problems (and fixes) I ran into, let me know and I can send it to you or post it here