If several of us are working on this, it would make sense to choose a common language. If you're all doing PHP, I have used it a little before, and I should be able to pick it up pretty quickly.
Since I assume this site will host stats for all projects, I'm thinking that, in order to make the stats programming as easy as possible, stats processing should be split into two parts. The first stage converts stats into a format common to all stats pages. For example (and no need to stick to this exact format):
Line 1:
Project_name, Last_retrieval, Primary_stat_name [, Other_stat_name [, Other stat name ... ] ]
Subsequent lines:
Username, Team_Name, primary_stat [, other_stat [, other_stat ... ] ]
Then we could write a common second stage that converts this to the pretty stats page.
Edit: Just looking at GeoffS's page now. How do I get per-team member stats?
