I, too, have a few things I haven't caught up yet from Liz filmography/guest appearances list. I keep saying I will watch them, and then forget/don't have the chance.
Gia really is a must watch. Liz's role requires all the subtlety we've learnt to love in her acting.
A lot of people had already watched it before Liz got on Lost, but I watched it only a couple of years ago, when I got curious/interested about the actress behind Juliet.
I think before Lost I had only seen Liz in Santa Clause.