Heroku only has 100MB of file storage, right? I'm making a low-level rails app and I really like Heroku, but if my app allows each user to upload one picture, I may run out of space quickly...is there a simple solution that will allow me to have alternative file storage for profile pics or something of the like?
I would recommend you to check heroku add-on solution which is https://addons.heroku.com/cloudinary. You will get 500MB for free and easy heroku integration.
For RoR app you can check: https://devcenter.heroku.com/articles/cloudinary#using-with-ruby-on-rails