Mainly Maximus Arcade. Its a bit buggy, and it REALLY needs an update from the developer. But found I it was quite a bit more easy to setup and build my own custom GUI's with so that it matches the project i'm working on better. If i do an RPi build down the road i know theres a couple simple and bad ass front end packages for those as well.
Truth be told, i'm trying to work my way away from things that have the need for a Front End. My builds are starting to gravitate toward things that have the GUI already built in, like the ArcadeSD, and these little Namco Plug-n-Plays. Just one less thing to have to deal with.