The advantages of using this system are obvious. On one hand, the stability of the browser is greatly improved by preventing one poorly-running tab from affecting the rest. On the other hand, it reduces memory usage since the closed tabs free up the resources they were using.
Stainless is still a relatively new browser that doesn't offer too many features, but one of them has been implemented in an original way. We're talking about the favorites feature that lets you just drag and drop the favicons from websites to a side bar.
For Mac OS X 10.5 or later.