Yeah, Coolrom is a good one, I've been there. Another one is emuparadise.org. And who could forget www.zophar.net? Although that one's mainly an emulator site... Anyways, good DS/GBA/maybe GBC/ maybe GB emulator: No$GBA. Good N64 Emulator: 1964. Good GBA/GB/GBC emulator: VisualBoyAdvance.
P.S. I'm gonna move this topic to general disucussion; it doesn't belong in announcements.