There is a new cloud storage service started called Copy.com it is cross platform including iOS and Android (Mac, Windows & Linux). At the moment they are offering 5GB free storage and and additional 5GB for each person you refer. If you are referred to Copy.com you receive 10GB just for signing up! Really useful service and a nice alternative to Dropbox.
Copy.com 10GB referral link
If you tweet about the service after signing up you receive another 2GB!
12GB cloud storage in just a few minutes!
Make sure to activate account after receiving email confirmation to receive additional storage
I just signed up and thought I would spread the word since it looks like the referrals for free storage is a limited time offer thing. It has been working great for me so far.