Julius Eckert has made splashes at TUAW before, namely for his Bezel HUD and Showcase interfaces for Quicksilver. Now he's released a beta of his much-anticipated Silverflow interface (inspired by designer Jono). The Cover Flow thing may be played out for some, but I'm finding this interface to be both elegant and useful.
I'll admit that I've gone from a die-hard user to watching Quicksilver from the sidelines, mostly due to crashes I was experiencing with it since upgrading to Leopard. I'll also admit that I had high hopes for further development when the developers made it open source and have been a little disappointed. But Silverflow has rekindled my interest and after loading Quicksilver back up to try it out, I quickly remembered all of the extra reasons I had for preferring it to Spotlight. Whether you're a current Quicksilver user or you're in my boat as a previously rabid fan, this beta is worth checking out. Do note, though, that it is a beta and has some missing functionality and known (and possibly unknown) issues. I'm pretty enamored, nonetheless.