PaperClip: An Alternative Attachment / File Upload Plugin for Rails
In Goodbye attachment_fu, hello Paperclip, The Web Fellas present a walkthrough of Paperclip, a new(ish) Rails plugin that makes file (and particularly image) uploads easy. It's well worth a read, especially if you're just starting to develop a new app and are looking at which file upload technique to go with.
Paperclip is compelling firstly because it's developed by thoughbot, a team of ridiculously talented Rails developers who've released a lot of awesome Rails-related projects (such as Shoulda, Factory Girl, and Jester). Secondly, it offers some awesome features: no extra database tables needed to refer to files/attachments, only one library required for image processing (ImageMagick), and a very easy way to refer to files (as attributes on the main model, basically).