Adobe AIR: Note-taking application Scribbly lives in your system tray and lets you quickly write notes or reminders to yourself, and then will email them to you with a single click.
Once you've installed the application, you can simply click the system tray icon to bring up the single note-taking window, type in whatever note you'd like to send to yourself, and then send it off with the click of a button—you'll need to set your email address in the settings, of course. The notes persist even after you minimise the application to the tray, so you can use it to take little notes throughout the day, and then email them to yourself before you go home.
The application is very simple, but where it could be really useful is when you combine it with Gmail's plus-addressing feature —just add something like [email protected] to your email address in the settings, and then setup a Gmail filter to automatically put those notes into a separate label for storage. It's a useful feature that makes it worth a look, at least. Scribbly is a free download for all platforms with Adobe AIR.