TaskFreak! web based task manager / todo list written in PHP
http://taskfreak.com
"TaskFreak! is a simple but efficient web based task manager written in PHP."
How To Launch Software (Aaron Swartz's Raw Thought)
http://www.aaronsw.com/weblog/howtolaunch
"Instead what happens when software developers try the Hollywood Launch, and I've seen this many times, is that users indeed do flood to your site on launch day but... Tomorrow, hardly any of those users come back. Your traffic graphs look like the sharpest mountain you've ever seen: a huge climb up and then, almost immediately, a similarly-sized crash back down. ... So what do you do then? Well, you do what you should have done all along: you grow the site."
Project X
http://www.projectx.com/home.html
I almost thought this was Tinderbox at first, from the screenshots. "Project X will forever change the way you manage projects."