Second Fafhrd/Grey Mouser book. Excellent stuff. Terry Pratchett wasn't kidding about this being an influence on the Discworld books. (Viz. the treatment of guilds and secret entrances in "Thieves' House" and "Men at Arms"; crossdimensional shops in "Bazaar of the Bizarre" and "Soul Music"...)
I was particularly taken by the narrative ingenuity demonstrated in several of the stories -- there are a couple here where Leiber avoids narrating tedious (or, sometimes, quite interesting) bits of story by having someone else tell it.