Here’s a new project that might be worth keeping an eye on if you are using OSX : Tominated Browser.
The Tominated Browser still lacks a lot of feature, but it’s very fast, The HTML engine seems to be a recent version of Webkit and the author seems to focus on creating a light and stable UI.
Although the lack of basic features like tabs and keyboard shortcuts is a showstopper to make it a default browser, this is a project to follow.