I'm fond of DEE and Big's designs as well. They're Haloish, and simple...they just seem to stick.

Chain's stuff looks pretty cool too, but I'm not sure if the Synapse icon is exactly fitting.

rentafence's are snazy and fitting (as they're quite literal)...however, I think they may be a little too detailed. MrBig's would at least transition well into an application icon and still look good at a higher res