If I created a blog, I add the article, sometimes it will related to other aspects, such as a fitness blog I write, to discuss how to improve their physical fitness, which will talk a lot of exercise, such as football, basketball, etc.,when related to these contents, it is good to create a blogroll with this blog? or in create a new sub-category related to good?
If you are looking for categorized blogs try to use sub domains for that its a much more easy practice.