I do make use of the blog categories to try to limit the amount of out-of-band content general readers need to endure. For instance I'll often put .NET code tips only in the .NET section, and SQL code tips only in the SQL section. When they are very specific technology specific items, I don't propagate them to the home page either, so you'll only see them in those categories.

I mention this only because I know some readers interested in SQL or .NET specific stuff only subscribed to the root RSS feed, and unfortunately they'll miss some of the content that way. For them I'd recommend subscribing to both the root feed along with the category specific feeds.