The product I use is Stardock ObjectDock. There's a free version that gives you a zoomer dock (the icons in the dock enlarge when you mouse over them). For $19.95, you can purchase ObjectDock Plus, which gives you tabbed docks in addition to the zoomer.
I've got Plus, and I love it. I have a zoomer on the right side of my screen for my frequently used applications. At the top of the screen, I have several single-tab docks. These act like little drawers that slide out when you mouse over them. Each drawer contains a different category of applications, like office apps, media players, games, development tools, and so on.
The fun part of ObjectDock is that the background is skinnable and you can get custom or themed icons for it. My favorite place to get icons and backgrounds is the WinCustomize ObjectDock Gallery. (I think you need to register at the site to download stuff, but it's well worth it.) If you don't want to register, deviantArt also has an ObjectDock category and generic dock icons.