[Vorph]

First, get Bookburro for Firefox. Then do an ISBN search at Amazon for what you want (in your case - 0786916575), and use the Bookburro interface in the top left to find it pretty much everywhere else (have to add BN.com and a few others manually in preferences if you want to see their hits).

Amazon.com: Used and New: Servant of the Shard (Forgotten Realms: Paths of Darkness, Book 3)
AbeBooks: Search Results - ISBN 0786916575
Half.com / Books / Servant of the Shard
Powell's Books - Servant of the Shard (Forgotten Realms Novel: Paths of Darkness) by R A Salvatore