Google Chrome recently introduced extensions for the Mac beta version. Extensions were already available for the PC and Linux version.
Extensions are a great way to enhance your browsing experience but most users don't use them and probably never will. A shame though, cause they can really be great for blocking ads, blocking Flash, syncing your bookmarks across multiple platforms and browsers with Xmarks Bookmarks Sync and much much more.
A little known fact however is that you can even use Greasemonkey scripts as extensions in Chrome. This gives Google Chrome even more extensions and possibilities.