or you could expand beyond bands that sound like weezer or green day.
Bands like Green Day plenty.Bands like Weezer,i know only of Ozma nevertheless you could give some of these bands a listen http://www.last.fm/music/Weezer/+similar
get pandora, listen to whatever pops up
Nirvana sounds nothing like weezer or green day.
and they sucked.
Lately I been listening to Nirvana a lot.