I was wondering if there was an open source program that would allow me to have a certain keystroke/key combination pressed every say, two seconds or so.
Yes, there is an open source program to create fake keyboard and mouse inputs for GNU/Linux. It is called Xdotool .
To press a key (in this example 'a') every two seconds you can use a script like this :
#!/bin/bash while true; do xdotool key a sleep 2 done
If you make this script executable and add it to Startup Applications it will press 'a' every two seconds.