Extra free 1GB from Dropbox via Mailbox app for iOS
1. Install Mailbox.
2. Log into Gmail account via Mailbox app.
3. Link to your Dropbox account.
4. Verify that 1GB was added by logging into your Dropbox account.
I believe you´ll need iOS6 on your iphone/ipad to install this app. It also sounds like you can link the mailbox on your device to multiple Dropbox accounts and receive a bonus 1GB for each.