Google Chrome on Mac OSX6 / 4 / 2009
Chrome is built from Google's opensource project Chromium. I installed it and give it a whirl, it's definetly buggy as hell. (The search bar stopped working randomly etc.) But some of the cooler features like dragging a tab off the tab-bar to create a new window worked well; dragging the window back to the tab-bar also works.
I looked all around the Google Chromium project page but there aren't any links to compiled code to get a .DMG to test it out for yourself, but here is a link to the nightly builds (via i use this). The most recent build is in the folder at the bottom.
It's definitely not ready for everyday use since you can't get Flash to work yet and it is very buggy. But if you are looking for "Chrome-like" speed on your mac, you should definitely check out the nightly builds of WebKit! It uses Safari's preferences and interface but it runs as a separate app.