Something cool: real-time collaboration in Eclipse via XMPP. The point here is that with the ECF Datashare API, it's possible to send arbitrary messages to folks on your XMPP (or Google Talk, or soon Skype) buddy list, and with the new Eclipse 3.3 menuContribution API, it's very easy to create your own plugin, that uses ECF's MultiRosterView to add on your own actions (like making a Skype call, or sending an URL to team mate, or playing Sudoku with a buddy, etc). No need to understand XMPP, to use any of this, just send/receive data (byte []s).
Now available via dev/integration build. See here for links to latest download.
Here's a class which is responsible for sending/receiving the URL (most of it is UI code. See sendURL and handleMessage/showURL).