Hola,
I'd like to let you folks know about a little javascript tool that I released earlier today. It's called boomerang, and it helps you measure web performance from your end user's point of view. It's released under the BSD license, and the code is on github at http://github.com/yahoo/boomerang/
Go check it out and let us know how you like it. Also, I'd love to have some of you contribute to it, so fork it and add stuff.
Thanks,
Philip