For C64 there is a frontend called Gamebase64. It runs very good, needs a bit configurating though. You can also install other emus with Gamebase, like GamebaseST, GamebaseZX, GamesbaseAMY...

You need a special C64 games folder though, a TOSEC does not work, as it uses different names for the games. But you can found it on p2p networks, search for Gamesbase64, you should find it in v3, v4 will soon be released.