[fitzsim]

Typing on the keyboard is surprisingly fun.

For larger programs you can interact with the Lisp Badge via a serial console. Here's a setup for using Emacs's built-in serial support. This makes programming the Lisp Badge very similar to working in SLIME, with an on-target REPL and the ability to evaluate code fragments onto the target:

http://forum.ulisp.com/t/emacs-for-programming/236/13

I used that mode to port Emacs's Tetris to the Lisp Badge:

http://forum.ulisp.com/t/tetris-on-the-lisp-badge/945

After (save-image) and unplugging from serial, I had a portable Lisp-hackable handheld gaming system. I made small tweaks to the game code -- like new cheat modes or modified sound effects -- with the built-in keyboard.