Magento vertical menu for product categories

Here's something about creating a vertical menu for Magento product categories. Ok. As a beginner in Magento theming, it took me quite a couple of days just to catch the right solution for what was required in my previous project - a theme with its custom homepage having vertically positioned menu. I kept googling that time and luckily found this very helpful wiki in Magento community. Here's a link to that. If you're interested, you really need to read it.