Off the top of my head I would say only Garden’s of the Moon and Midnight Tides stand alone well. The rest involve to much back-story, and trust me, if you don’t have that back-story, it’s incredibly confusing.
Memories of Ice stands alone just fine.
I’m trying to remember what happens in the book that spends the first third following the adventures of Karsa Orlong.
-Joe
That’s House of Chains. It’s mostly Tavore against Sha’ik and the Whirlwind. Definitely doesn’t stand alone.
Dunno, I definitely think that Gardens of the Moon could stand in the “very confusing if you don’t have the back story” category. But that’s part of the charm. 
I suppose Memories of Ice could work, if you ignored the constant references to the previous book. And Kruppe would probably confuse the hell out of you. Not to mention when the Trygalle Trade guild shows up out of nowhere. House of Chains doesn’t stand on it’s own. For it to make sense you’d have to know that Sha’ik is Tavores sister, and the whole Chain of Dogs backstory, and who in the hell Fiddler is, and who Crokus and Apsalar are, and a whole bunch of other things.
ETA: Rysto beat me to it, I see. As I said I started on the second book and there’s a point where it goes from nice and mysterious to “WTF is this? What’s going on? Who are these people?”, and it’s just kind of unpleasant.