The usual recommendations for a web development and debugging web browser are Firefox/Firebug or Safari/Web Inspector.
But I like Google Chrome, and would like to use this as my primary development browser. What plugins or tools should I get to optimise my web programming experience with Chrome?
Google Chrome's own "Firebug" is very good, just right click and inspect element to bring it up.
Frame two pages is helpful.
Chris Pederick's Web Developer toolbar is good too.
The Development and Coding Search (Chrome extension) is one of many Chrome extensions for developers. See the featured web development extensions for more developer-friendly extensions.
Pendule has a lot of good bits and bobs under one extension/icon. Few things I like about it...
There are probably tons of alternatives, but it's the best I've seen so far.