PHP: PHP is well covered by Core PHP and PHP 5 Power Programming. For PHP with MySQL then Core Web Application Development With PHP and MySQL is well worth seeking out.
Google and SEO: Anyone interested in getting the most out of AdSense or AdWords should seek out Google Advertising Tools. Also recommended is Google Hacks - both from a user and programmer viewpoint. Finally, for a lool at search engine optimisation (SEO), then The ABC of SEO is a good read.
Ajax: There's a real rush of books on Ajax, but the TechBookReport favourites include Head Rush Ajax and Ajax In Action.
ASP/JSP: ASP.NET is well-covered by Programming ASP.NET and on the Java side Murach's Java Servlets and JSP gets a recommendation.
Other recommendations: Finally, no web developer can afford to take risks with security which is why we recommend Innocent Code.