At my open mic night, we have certain songs we always tend to play to encourage people to get up & play. These songs are pretty diverse - from stuff like John Holt 'Help Me Make It Through The Night' to Nirvana's 'Smells Like Teen Spirit' to Dubliners' 'Black Velvet Band' to 'Zombie' by the Cranberries.
I quite like the idea of having an eq setting for each song on a footswitch, and being able to knock it off for a request that I don't know.
Maybe one day I'll get to try it live...