Mac OS X: TinyGrab makes instant screenshot sharing a snap on the Mac. With a simple keyboard command and a free account, you can share screenshots in a matter of seconds.
Once you've installed TinyGrab and plugged in your account credentials, any time you hit Command + Shift + 4 your cursor will change to a crosshair. You can select all or portion of your screen which will be automatically uploaded to TinyGrab.
When the upload is complete a chime will sound and a shortened URL will be placed directly into your clipboard. Paste them link to share it and you're done. Check out the video below to see it in action.
The free version of TinyGrab allows for three screenshots per day. Upgrading to the $US16 premium account—a one time fee—uncaps your screenshot limit, allows you to search through your previously uploaded screenshots, and gives you the ability to upload screenshots via FTP.
TinyGrab requires Mac OS X.