Dwedit has popped up with a new version of his TI83 Emulator for GBA, heres the release notes:
Here is a Multiboot version of the TI83 emulator.
If you trim the TI83 rom, the file size of the rom is about 215900 bytes large.
You can also attach a .83G file up to about 14000 bytes large, and use L+R to send it.
If the GBAMP firmware refuses to boot the file, use the PocketNES firmware instead.
Edit: Using Pocketnes firmware to run the emulator may be buggy. It crashed when I tried sending a game to the emulator. Using GBAMP's firmware didn't boot the emulator at all for me.