A bunch of ExtremeProgramming enthusiasts recommend
MoreSecretsOfConsulting by GeraldWeinberg
(ISBN 0932633528 ), which is now my most recent Weinberg read.
It is really a quite wonderfully subversive book. As much (and as little ;-)) to do with consulting as ZenAndTheArtOfMotorcycleMaintenance has to do with motorcycles. Nicely done with bite sized nuggets... tools from a tool box is the metaphor, a short chapter on each tool without too much "read in this order" dependency. Humorous, succinct, and salient examples illustrate the ideas, very helpful. The humor is what makes it subversive, lets one absorb new ideas by bypassing one's defensive filters. One of those "you get out of it as much as you put in" kinds of books, though I'd guess that even a quick/light read would plant some seeds... -- DougPhilips
Also see SecretsOfConsulting by the same author.