The apparently unexciting circle on the right is the main interface for DropCopy, a very cool little application for sending files between computers on your local network. First of all you need to install DropCopy on all the Macs on your LAN. When it is running, this little circle appears on your desktop and when you drag a file to it, a list of destinations (i.e. the other machines running DropCopy) will pop up. You choose the one you want and the file will "warp" to the other machine, no fuss, no muss. In addition to copying files you can also retrieve the clipboard contents of other machines running DropCopy (e.g. you can copy something to the clipboard on one machine, turn to another machine, retrieve it and paste it). I've found DropCopy to be the easiest and fastest way for sending a couple of files between machines on my home network (though you may have to open port 5052 on your firewall).
DropCopy is donationware on networks with 3 or fewer Macs, and $25 for larger networks. It's definitely a convenient time saver.