Helvetica Neue Ultralight: duh
Big Caslon: so elegant, but the sharp points are menacing at the same time; kind of like how stilettos are both dangerous AND feminine.
Tw Cen: similar feel to Gill Sans, but not nearly as recognizable
Din: thanks to Sarah and Renovate | Style, I really enjoy the versatility of this one. It can look fun (light) or serious and technical (condensed)
BlairMDITC: used a lot on book covers, and looks great with lots of tracking and kerning
Rockwell: I can never make it look good in my own work, but really appreciate it when I see it done well in other design
Comic Sans: ha, just kidding! I appreciate you even reading this far.