You may be aware of the extra space that Dropbox gives up to 3GB extra space free for the uploading of Photos from your smartphone and now also from cameras and memory cards attached to your PC or laptop. See here… https://www.dropbox.com/help/287/en
However if you would just like the extra space without using it long term for photos, you can gain all 3GB of extra space in one hit.
Simply plug in a memory stick or external hard drive to your PC or laptop and create a top level folder called dcim (if your drive letter is F: then this folder would be F:\dcim ) .
Then copy 3GB + worth of your photos to this folder. Once copied over, safely remove the storage drive from your PC. Making sure Dropbox (version 1.4.7 or higher) is running on your computer, plug the external storage drive back in. Dropbox will automatically scan this new folder and start uploading the photos, first to your Dropbox folder on your computer and then up to the Dropbox web storage (please make sure you have enough free space on your computer to do this)
Now sit back and let the upload take place, eventually you will gain an extra 3GB of storage for free.
Once you have all your extra storage, simply delete the photos from Dropbox, making sure you do have a copy of them elsewhere of course! 🙂