5 Places Your App Can Store Data That Aren't MySQL

Yesterday I was working some code for a client that had me storing data outside of the usual MySQL setup. That got me thinking, what other data storage options might I be overlooking? Here's some brainstorming of places that are easy to stash data (and all have web friendly APIs).

1. SimpleDB - SimpleDB gives you the ability to store massive amounts of data on a platform with high-availability built in. Related: Cloudant.
2. Twitter - Twitter provides the ability to store a stream of data in a way that users can view it from a variety of platforms, all without you developing special interfaces. You even get SMS notification and RSS built in for free. Related: WordPress and Blogger.
3. Google Spreadsheets - Why store data in a database and then write code to extract it into a Spreadsheet, when you can have your app talk directly to the spreadsheet? Skip the middle man. The Zend API allows you to do this in just a few lines of code.
4. Pastebin - Pastebin allows you to inject a chunk of text into their system and get back a URL to it. The data provided can be rendered with code highlighting, have an expiration date and be public or private. An interesting set of options which are provided by using a super simple API.
5. QR Codes - why not stash your data in an image? Each QR code can store up to 256 characters. Push the resulting images to Picasa or Flickr. Or better yet, print them out and have your data literally in the palm of your hand.