AppHarbor (like Heroku) doesn't allow you to save uploaded files or images. I need to offload this somewhere and I have no idea what services exist for this purpose.
I've looked into FilePicker.io but they display a tacky branding image in their uploader and to remove that branding you have to pay a large sum of money.
Any suggestions on how to approach this problem? What is the modus operandi with applications that need file uploads that are hosted on PaaS?
We recommend that you use Amazon S3 to store files like this. An AppHarbor user has written a guide on how to get started with S3 on the support forums.