Quicksilver is a really impressive application that I believe makes a significant improvement to the desktop UI. I don’t think I’ve used it but I’ve seen the Google talk recently, and then heard that it was open source, but sadly still not available on Linux. I have also been a big fan of Gnome-launch-box ever since it came out, but I was getting disappointed that it hadn’t progressed much and by comparison was very basic and a little slow, so I was really delighted to come across GNOME Do today. It’s lightning fast and has some nice features that I haven’t even explored yet. David Siegel has done fantastic work with this and I have no doubt it will be rapidly adopted and widely adored.