I've just started using Chrome as my main browser and I recommend the Pendule extension to everyone who's not already using it.
It's like the Web Developer Toolbar for FF but has a more compact and clean interface. It has many useful features for investigating CSS, colour, images, browser resizing, validation, ruler etc.
Give it a go and tell me what you think. Or if you're already using it, tell me why you haven't recommended it yet!
Awesome Screenshot - full page screenshots
Adblock - easy to disable when you need to view the web "raw"
Firebug Lite - obviously