Romeo is a Java-based MAME frontend. It supports XMame and the Windows command line, and it has a lot of features. This application is skinnable. It can automatically download ROMs, screenshots, flyers, and other related types of media. A different config file can be used for each game.
asq is a simple frontend for MAME/emulator cabinets. It runs in a terminal window using curses, and pops up an optional screenshot window. It uses MAME/emulator keybindings so you can control your MAME cabinet using just your MAME controls. (In fact, this is where the name comes from--player 2 buttons 1, 2, and 3 are "asq".) It can also remap your games to use MAME keys. asq is meant for people who don't want to use a keyboard and have lots of games to manage.