Emulator fans rejoice! Or at least smile!
The new
Zeta Joypad is a new game pad add on that can be attached to your iPAQ to give better gaming experiences when you are playing
Double Dragon 
or other retro games.
"The product works with emulators like PocketGB, PocketSNES, iMAME, MAMECE, PalmGB, CE/gg, NeogeoPocott, PocketFC, PocketNES, METARION and Turjah"
Source:
Geekzone article