Don't know if this has been mentioned here yet, but it looked pretty cool to me. http://users.skynet.be/firefly/gba/e-reader/index.htm
be sure to check out the Nintendo e-Reader NES Compatiblity List at all working games. The "NES" type are actually mapper 0 roms that run on the built-in NES emulator.
Look like I might pick up a E-Reader now.