"This product is an essential magento extension for anyone wanting to create categories with dynamic products. Particularly useful for sale periods as you can set it to show products that have the special price attribute within a certain date. Also very useful for brand and product range pages (especially for SEO) assuming you have created the correct attributes, as soon as you create a new product it gets put in without any further work. It pretty much works with all created attributes, so as long as you assign attributes to your products correctly, you can create a dynamic category around that. The developer is very active and will help out with modifications or added functionality where possible."
OpenMage Dynamic Category Products
