At the UPHPU meeting last week, Ray Hunter discussed the development IDE Eclipse. He even packaged together a version of Eclipse specifically for PHP. (He has taken out all the extraneous stuff.) If you’re a PHP developer, you might like developing in the Eclipse environment. P.S. I haven’t tried it yet.
The other main topic at our meeting was AJAX. The consensus was that Xajax is the best library for quickly and simply adding AJAX functionality to your PHP app.
PHPEclipse does code-hints, phpDoc mouse-overs, syntax highlighting, and code-completion for Smarty templates. It does much more than that, but those are some of the features I especially enjoy.
I’m not sure what extra php plug-ins the UPHPU has added to their IDE package besides PHPEclipse (which I assume they’re using).