ShowSlow collects web performance data and shows it in aggregated form trended over time.
You can see working public version of the software at showslow.com
Documentation wiki can be found at showslow.org - feel free to contribute!
You can ask questions and discuss ShowSlow in our group: http://groups.google.com/group/showslow
We also run feedback forum here: http://showslow.uservoice.com