Yes, L+R+A+B+Down to get back to AKAIO, L+R+Start+Select in most games (it's a function of the game) to reset back to the game's title screen.
If you want to soft-reset from homebrew, you'll need AKAIO 1.6 RC1, and it doesn't work with every homebrew, but there's two modes you can switch between in the global patch settings, and one of them should work (except with moonshell, which can just run the akmenu file to get back to AKAIO).