Yesterday was a banner day for Wii homebrew. In addition to WiiPaint, a load of console emulators designed for Twilight Hacked Wiis were also unveiled, and DCEmu has rounded them up. They're all based on existing Gamecube-based emulators, but have been extended for the Wii to take advantage of features like the Classic Controller and the Wii's 480p output. Lopst's and RobertFC's ports of SNES9x even allow you to use the Wiimote! In case you always wondered what it would be like to have a really hard time playing an SNES game.
In addition to an SNES emulator, new PC Engine/Turbografx-16, Genesis (with Sega CD!), and Game Boy (which installs into a channel) emulators are now available.