One of the things that was important to me in starting a new blog was the ability to combine all my blog posting into one blog instead of multiple blogs for each type of content. The problem is that it is considered proper blogging ettiquete to focus one general subject in a blog so that anyone who happens on by can more easily find the information they are looking for.
Enter per category feeds. This adds a whole new level of flexibility with my blog. Now I can provide feeds that are specific to categories or tags, and not worry about being all over the place with my content.
Next…trying to import from blogger & livejournal.