Question: I know of a couple tools to measure end user web site performance and I'm wondering what else is out there. The two major ones I know of are [yslow](http://developer.yahoo.com/yslow) and [Google's page speed](http://code.google.com/speed/page-speed).

Answer: 
[Octagate's Site Timer](http://www.octagate.com/service/SiteTimer/) provides a graphical view of the load time if you want a web site, or you can get similar statistics with Chrome and Opera's developer tools.

![Octagate example result](https://i.stack.imgur.com/M0AA6.png)
![Chrome example result](https://i.stack.imgur.com/fxcap.png)
![Opera example result](https://i.stack.imgur.com/mlYj6.png)
There's a very good metric that never fails for when we tweak (or sometimes un-tweak) our highly successful website. If the pages are even 0.5 of a second slower, sales drop by up to 30%. Sounds crazy, but it's true. When I remember to enable GZip compression and minify our JS/CSS and switched to sprites our sales went up.