it's funny how they decide to give out invites. i had an account for over a month and not one invite. then one day i get one and i send it to my friend. the next day after he opens his account and he's got an invite already. luckily, the day after that, my account suddenly got 6 new invites!! i'm not sure how they do it, but i guess you'll get some sometime.
btw, the invites are already given away so please don't pm me about them.