Thanks, everyone!

These answers are really helpful. I did just try UD 24/7 (Rockstar - love that color) on the waterline and it works really well...and I picked up a few MUFE Aqua Pencils, so we'll see how that goes. The MAC Power Kohl (Sense of Style way more than Feline, interestingly enough) is a total bust, though - I will just stick to my upper lashes with that one. The color's pretty, though.
I am afraid to try MAC Fluidline or Bobbi Brown gel liners (as much as I adore them) on my waterline. If anyone else is brave enough, though, please report back!
Hielo - sorry to hear about your mu bag.

I know that I would be super upset if I lost mine, too!