It's a little Toolbar (written in JS+CSS), which keeps track of all stuff happening in your php agavi application. So you can easily spot memory leaks, time exhausting tasks and extensive usage of database queries (with the doctrine or propel extension).
The source can be found on github now http://github.com/DracoBlue/PhpDebugToolbar, feel free to fork it and send pull request with new features!
Licensed under the terms of MIT.