If you use FBA-XXX, then you can use a command line switch to boot directly to a game.
None of the MAMEs offer that ability, but many of the console emulators do (All of the ones ported by Xport + some others).
I'd start digging around the
xbox-scene forums, as there is a ton wealth to be found there.
For my Xbox arcade cab, I am running Unleash-X as my dash. It is extremely customizable, and has plenty of options that made for making a nice arcade cab gui. Plus it does allow for command line tags, so I am able to boot directly to any Neo-Geo, CPS(2), etc... game.