I have the luck of living in LA and being able to go this year to E3, but I'm extremely curious about if there are after parties associated with the different companies. Are these open to anyone or does on have to be on a list to get into the parties? Also are there any Giantbomb community meet ups happening?

Giant Bomb does their podcasts at night after the show floor closes, so I doubt they will have any official meet ups. There is probably some kind of requirement (invitation, or a press badge or something) for attending any official after parties, but I don't really know. I think they were more lax on these things years ago.

pretty sure 99.9% of all e3 parties are private and have guests lists etc. but seen many companies do giveaways for tickets. so likely would be pretty easy to get in by either emailing someone in the company or striking conversation at a booth or something.

Just rock up with confidence and you should get in no problem.