Eh, last time I tried snes9x it had some rather buggy frontend that had most of the options missing, but I think it was at least able to configure the controller, though I may have been thinking of nestopia. Also, I tried desmume and it was just ass. I can't get it to run well because a lot of the options in the windows one were missing, then it crashed so I didn't really care to edit the config file. :/ I also tried dolphin, whose interface was just the most broken thing in the world, but I guess it's the same amount of brokenness in Windows.
So I suppose the older consoles have gotten better for frontends, but the newer ones still have a lot of trouble. It's nice to see stuff like Qt and GTK+ becoming popular for freeware/open source projects, so they can just be moved over to Linux without stripping out the win32 api based interfaces. The next step is to just get emulator authors to stop using directx.
But this is way off topic. A decent frontend would be nice, but the pandora already has a bunch of frontends. It would be nice if these frontends could be expanded on for stuff that runs/plays in stuff, even usable for music, videos, ROMs, VM-based stuff... I think the only ones I know of that are that versatile are like, XBMC and a few other really large media center frontends aimed at consoles/desktops, but that might just be a bit big to run in the background at all times while you're playing a game, given the amount of RAM available. Such functionality for a basic list of files with an automatic "run with ..." option probably wouldn't be too hard, but if you want special fields like genre, year, etc or screenshots for things, it might be a bit more complex, depending on how much you want to add. I imagine for something aimed at the pandora, you'd want to keep it small on memory and light, so a full scriptable system probably would be a bit heavy, but then the needs would probably be a bit more specific, since most people will just want to use their PND games and apps, play music and video and play ROMs and things like that, so a simple "run with..." with a list of files would be enough.. then if it's reasonable, add the ability to show extra metadata from a file (maybe something that can be downloaded online?) like full game titles, genre, year, number of players, input methods, etc. Too bad I'm too lazy to do something like that. :/