Tool for measuring on screen?

In my curiosity I'm many times interested in seeing measurements, or approximations of what I'm viewing, say on a Webpage. Anyone know of a tool that might do that?
Thanks

cool ruler may do it

http://www.softpedia.com/progDownloa...oad-40393.html

http://www.iconico.com/caliper/

Mike

plenty of extensions in google chrome (I use one called ruul)

A simple tool for screen measuring, very easy to use is the ScreenRuler from about.com:
Attachment 96624

http://delphi.about.com/od/fullcodep...reen_ruler.htm

@sketch thanks for sharing that - its brilliant - just what is needed - :-)

All you guys are too much..perfect and thanks a bunch.