If you are a Dropbox user and have an Android phone, here is good news for you: you can get an additional 1 GB of free space for your Dropbox account. Dropbox is currently providing it as a gift for new Mailbox for Android app users. Get it while it lasts.
Point your device to the following link: Mailbox for Android. Alternatively, you can type the following in the Google Play search box:
Install the Mailbox app.
Open the Mailbox app you installed and sign in using your Dropbox credentials.
The additional Dropbox space should appear instantly after your have signed in.
Later, if you do not like or do not need the Mailbox app, you can just remove it: the additional 1 GB of space will remain.
This offer was earlier available for Mailbox for iOS users, now it's available for Android OS too.