The pastebin Plasmoid, in KDE 4.2's kdeplasma-addons module, is really neat. As annma pointed out to me on irc today, you can drag images straight from ksnapshot onto the pastbin Plasmoid and it uploads it to an image site for you and then displays the resulting URL. You don't even need to save the image first.
The pastebin Plasmoid also supports text, of course, but that image trick scores higher on the cool factor. I hadn't even thought to try it with an image. =)
That one little Plasmoid makes collaborating so easy: drag, drop, share!
KDE rocks. =)