Through this simple blog, I have been referring new users to copy.com. Each time you refer a user, both the new user and the person who referred him gets 5GB extra (so the new user actually gets 20GB = 15GB + 5GB). So far, my storage capacity is now 60GB (I referred 9 users already, so my bonus space is 45GB).
Now, I'm not doing it for the extra space. I actually currently only use about 10GB, which is probably enough for most users. I blog about cloud storage because I find it interesting technology and because I want to share my personal experiences. So far I use 2 cloud sync services: copy.com and mega.co.nz. I have tried out and used others (Skydrive, Livedrive..) but so far copy and mega are for me the best 2.