I am approaching the limits of my hosting plan. I doubled it once from 2 to 4 GB and my site (a popular woodworking community in Hebrew) is getting close to using the disk space available for the images people are uploading.
I was wondering if it were a legitimate use of DropBox (or any of the other free cloud hosts), to serve the files of it as public files... i.e. whenever someone uploads a file to my server it will be instead uploaded using the DropBox API to the DropBox servers, and the Public LINK to the file will be stored in my DB and served to the users.
Another option would be to upload to a hosting server in GoDaddy (I can afford those prices), but that would require writing my own client, which isn't ideal (a good exercise, but I don't have the time).
Obviously the site also generates a fair amount of traffic, I would not ask if it were for personal/close friends usage, I'm talking about many thousands of hits per day...
Update: an answer and comment mention that "Dropbox public links have a bandwidth limit. 20 GB/day for Free and 200 GB/day for Pro." https://www.dropbox.com/help/45 - this seems to suggest that as long as my bandwidth requirements are somewhere below this number, then I am in the clear... Is that so?
Dropbox has bandwidth limits. I use it quite often for running simple static websites for internal testing, but it there are limitations.
Take a look at this: https://www.dropbox.com/help/45
As far as I know, Dropbox "Free" is only for private usage. They also have business plans. I would consider to upgrade your existing host for a few more dollars.
Look in to Rackspace Cloud Files and Amazon S3. You can hotlink directly to the files.
Alteratively, have your users use an image hosting service like Flickr or photobucket, and have them provide links instead.
Whether it's legitimate or not, Dropbox will no longer allow it as of 2017. From https://www.dropbox.com/help/16: