Lots of folks, myself included, like Head First Servlets and JSP. It's designed as a study guide for the Web Component Developers exam. The first part of the book talks about scriptlets, which you should never use for new development, but you'll probably need to understand them for maintaining old code.
You'll also find lots more suggestions and book reviews at the Bunkhouse.
"The good news about computers is that they do what you tell them to do. The bad news is that they do what you tell them to do." -- Ted Nelson