Mac: Slingshot gives you a single keyboard shortcut to take a screenshot, upload it to Dropbox or Imgur, and copy the URL to your clipboard to share with a friend. Everything takes place with one keystroke.
We've discussed other apps that will take screenshots and save them to Dropbox, most notably Dropbox Screen Grabber for Windows and GrabBox for Mac. Slingshot is different because it reduces the entire process to a single command, lets you choose between Dropbox and Imgur, and can take rapid-fire screenshots and upload them sequentially.
Slingshot is $3.99 in the Mac App Store, and available now.
Slingshot [iTunes App Store]