We use TinyGrab: <a href="http://tinygrab.com/download.php" rel="nofollow">http://tinygrab.com/download.php</a><p>As a design agency we are constantly sharing stuff between each other. You can configure it so it automatically uploads to FTP and copies the link. Really fast and super handy.<p>We've also been really happy with the dual cursor screen sharing tool Screenhero: <a href="http://screenhero.com/" rel="nofollow">http://screenhero.com/</a> when screenshots just don't cut it.
I recently discovered <a href="http://www.cockos.com/licecap/" rel="nofollow">http://www.cockos.com/licecap/</a> which lets me take screen captures and save them as gifs. Definitely helpful when trying to capture CSS animation bugs.