iOS: If you're a big fan of the audio note-to-self but you'd like more flexibility than the iPhone's default Voice Memos app, DropVox may be for you. It's a simple audio-recording app that links with and uploads M4A recordings directly to your Dropbox account.
There's not much to say about it beyond that. After downloading the app, you link it to your Dropbox account, hit record, and it automatically uploads the results. By default recordings go in a DropVox folder in the root of your Dropbox account, but you can set this to any folder you prefer in the app's preferences. (You can also set the app to record immediately on launch.)
Simple and effective, just how we like 'em. DropVox is a $1.19 download in the iTunes App Store.