A Bit Better Remember The Milk
If you're a Remember The Milk user, you should check out a plugin called "A Bit Better Remember The Milk." It takes your lists and moves them from tabs across the top to a list down the left side. You can drag the items in your lists around and put them in any order you like, and it adds a "Add List" button right on your main task list page!
I don't know if I would use Remember the Milk without it!
Do a search for it. There are different plugins depending on the browser. I currently use it in Chrome and Firefox.