I personally reckon that 2 bands who are really trying to be inventive in mainstream music (which gets harder and harder as time goes on) are:

The Flaming Lips - These guys used the recording studio to the max on their last album (Yoshimi battles the pink Robots), as well as releasing the album on dvd with probably the most ambitious 5.1 surround mix ever.

System of A Down - I mean has there ever been a mainstream metal band (nu or old) to have been so eccentric and still so heavy? They also hav a cool eastern vibe.

What do u reckon of both these bands?
Who do you think are the main innovators in mainstream music at the moment?

I have a ton of respect for these guys who manage to do something remotely original in a time (well, always) that record companies are very reluctant (and rightfully so) to take chances on unproven artists.