Show Slow is an open source tool that helps monitor various website performance metrics over time. It captures the results of YSlow and Page Speed rankings and graphs them, to help you understand how various changes to your site affect its performance.
www.ShowSlow.com is a demonstration site that continuously measures the performance of a few reference web pages. It also allows for public metrics reporting.
If you want to make your measurements publicly available on this page, see the instructions in Configuring YSlow / Page Speed. If you want to keep your measurements private, download Show Slow from the SVN repository and install it on your own server.