Tantric mentioned before he'd like this sort of thing with info for the games EG number of players etc. BUT he's so busy he won't do it himself anytime soon and imho if anyone else does it would also be crazy because we don't really want 115 different versions of the different emulators coming out.
If anyone could do this imho the BEST way to go about it would be to start on the code, contact Tantric, eke-eke or other Dev and tell them your intentions. Then once your code could be implemented best to get it implemented in the "official" builds.
Some of these Devs are one man armies at times and I don't think they wouldn't want the help, I'm sure they'd appreciate some extra working code that was efficient and tested to some degree and they would probably add it in to a future builds. Remember the most emulators coded are open source so you could submit your code to them and if they liked it and hosted it on google code, you might even get others to help.
There are no "really hard problems" here except for the one massive factor of TIME, it would take a LOT of work to get a good working DB of info for games as there are soooooo many with different covers per region too. They would need all resized to a standard that didn't mess up the interface, and also you gotta consider the size of them for users with no USB HDD who would be using SD cards.
The SEGA emulators coded by eke-eke would be nice to have this type of feature too, but I've never saw him mention he wanted it, and I'd think he'd maybe rather get things like SMB integrated first.
As for lots of the other emulators out there coded by other devs, it's easy to ask them if they wanted help everyone I've ever spoke with are friendly and appreciate help where they can get it.
Covers could be identified by several different things like the CRC or other header info and I'm sure there are many coders on lots of sites that could do these type things, but as I said before It's a LOT of work, don't underestimate that your talking about emulators that might have nearly 10,000 games (Snes has close to this I think). I just hope if anyone does this, they help with the "official" builds rather than make seperate builds that would look nice but quickly become outdated.
btw, this should have been posted in the
Wii - Emulation section really