Jimmy Eat World, Gob, Saliva, Slipkot, Fuel, Deftones, Vertical Horizon, Incubus, Default, Puddle of Mudd, Cold, Foo Fighters, Nickleback, Creed etc etc.
Out of this list, I only ever heard of Nickelback, Creed, and Foo Fighters. I have never heard of the other bands listed.
I suppose a definition of "mainstream rock" is very subjective. My definition would probably be out of date. What comes to mind when I hear the term "mainstream rock", are bands like Poison, Bon Jovi, Duran Duran, The Bangles, Aerosmith, Samantha Fox, etc ...
(I more or less stopped following current music trends around the time when bands like Nirvana, Pearl Jam, Alice In Chains, etc ... first became popular in the early 1990's and the movie "Singles").