They still have the 5 mystery bottles of OPI for $20. You can also get 5 mystery bottles of Nicole by OPI for $19. They have the entire China Glaze holiday collection (12 bottles) for $37 (i.e. $3 each) and the Orly Mash Up collection (6 pieces) for $31 ($5.17 each, which is not great, but better than in stores, I guess). There might be more, but these are the ones that came up when I searched "nail polish" on the site. I think the OPI one is still the best deal, if you are okay with surprises.
There also seems to be a lot of Elizabeth Arden stuff available at the moment, if you're into that.
Shipping is $2 per item. You can get a $10 off $30 credit by using my link to sign up (I get one too). And you can check out my review of my experience buying from No More Rack here.