You can't deny the beauty of Mac OS X Leopard, and all the new functionality is certainly a joy to use. But if a third party developer can come in and make some functionality better or more customizable to users I think it's worth looking at. One of the great things about Mac OS X and Apple in general is they pay close attention to design. But every user is different, which is why some developers make it possible to put your own brand of style on key interface elements of Mac OS X.
During my usual daily scouting of popular Mac sites, I came across a cool Dock customization app called Dockulicious. Dockulicious lets you drag-and-drop Dock styles to change the way your Dock looks to better fit your overall desktop aesthetic. The program is very easy to use, letting you play with different Dock styles from third-party sites.
Once you have Dockulicious (strangely called DockSwitcher in the file itself) on your hard drive, simply browse sites like LeopardDocks.com, LeopardDocks.net, or the Dockulicious site to find new styles. When you find one you like, download the zip file to your Mac and then drag-and-drop the zip file on the Dockulicious (DockSwitcher) icon. Though switching out your Dock is possible without the program by drilling down in your folder hierarchy and switching files, using this app makes it much easier. If you want to return to the default Leopard dock style, Dockulicious comes with a Restore.zip file in the original install folder to bring it back to the original Dock.
Overall, I think this app makes it pretty easy to switch Docks, but I wish they would get their app-naming convention straight. There's another DockSwitcher on the Web that modifies the Dock as well, but not with the ease of Dockulicious...I mean DockSwitcher...once you download it, you'll see what I mean.