The likelihood of you not knowing what Google Chrome is very very slim.... but just in case here is the link: http://www.google.com/chrome/
Must Have's
As a web developer my default browser must be able to handle certain developer needs (other than rendering the website/application correctly).
The most useful web developer tool is a very well known guru of an add-on for Firefox:
You guessed it Firebug!
So my first question is "What does Chrome offer?"
Goggle Chrome has it's very own "Inspector":
This is nice Google! Clearly based of Firebug, Chromes version has all the stuff (sorry for being so technical!) you would expect.
The UI is very much like the rest of the browser: clean, simple and nice to use. Far better that IE8's version of the Developer Toolbar.
To bring up the inspector you can either right click on any element on your web page and select "Inspect element" or select "Developer" -> "JavaScript console " from the Page menu 
.
What else?
There are loads of feature in Google Chrome...and lots of features to come, but as a web developer it renders fast, looks great, works well...and therefore I setting Google Chrome as my default browser...for now.
What do you think?