I don't normally post shit like this, but dropbox has some competition. For every user you refer you get 5gb, as well as the initial 5gb. If you accept someone's referral you also get 5gb. All files are shared based on the number of users. So if a 50mb file is shared between 2 users its only 25mb per user shared.
I love it.
https://copy.com?r=WTB8Kl