I use S3 on a number of project, the main one being MailTank.com, where we are securely storing an enormous amount of data for.

There is a lot to learn when integrating with S3 or any other remote web service. This article has a nice overview of the technical concepts.

Building on his Introduction to AWS for Ruby Developers tutorial, this second article from Robert Dempsey shows you how to efficiently make requests to Amazon S3.

(Via Use of Amazon S3 with Ruby on Rails.)

As you do more with S3, you will find yourself abstracting access away from the UI and doing a lot more in the background. Both to improve performance and also to manage costs.

This winter I will publish a detail article on what we have learned and how it has impacted our business.

Its safe to say, S3 gave us a huge leg up on our long term plans. Accelerating our product development roadmap, eliminating a huge expense and allowing us to get features to our customers much faster than we expected.