JLinkCheck is an Ant Task written in Java for checking links in websites. It is not just checking one single page, but crawling a whole site like a spider, generating a report in XML and (X)HTML. JReptator will be its succesor with many more features
openDebug is a simple PHP debugger for use in small websites.
openDebug will generate extra HTML/Javascript code which 'attaches' to the HTML output.
Then the coder can look up his variables, queries and check for errors.