Neat “Firebug for PHP” profiler/debugger tool.
#development
Appcelerator Titanium
“Titanium is the first open platform for building rich desktop applications.”
The Ultimate Website Launch Checklist
The Ultimate Website Launch Checklist
Nice list (available in PDF) to go through and check things off when launching a site.
Charles
Web Debugging Proxy | HTTP Monitor | HTTP Proxy | HTTPS/SSL Proxy | Reverse Proxy
maemo.org
“Maemo is the development platform for Internet Tablets”
three20
Generic iPhone library of widgets and UIs that was used to build the Facebook app, and could be useful for all sorts of other apps as well.
Quick Lookup
Nice AJAX-powered tool for quickly looking up PHP, MySQL, JS and CSS functions etc from their respective references.
11 Facebook App Dev Tips
Some good tips and tricks for developing FB apps.
Selenium
“Selenium is a suite of tools to automate web app testing across many platforms. “
XUL
XUL reference at the Mozilla developer center. Very handy for developing Firefox extensions.