Lots of good stuff in here. I listen to basically everything. Punk, hardcore, alternative, reggae, hip hop, dubstep, whatever. Pre-surf I usually can't go wrong with something fast to sing along to - Bouncing Souls, Rise Against, Four Year Strong, A Day To Remember, Misfits, Hot Water Music, or some old punk like Rancid or Op Ivy. Post surf is usually more mellow with some Jack Johnson, Slightly Stupid, Pepper, etc.
Day to day I listen to mostly hardcore and metal probably but really have a mix of everything on my iPod.