Here is an explanation of the categories that the different tools can be classified under.

Add Ons - This category is for something that really doesn't help your blog so much, but helps your site as a whole. These can include, but are not limited to hit counters, link management...

Blogging Applications - This category is for applications that you would install on your computer that allow you to blog.

Blogging Tools - This is the major category. Any site or program that you access through a webpage (yours or theirs) to update your blog.

Hosting - Pretty much self explanatory. This area will cover free and paid hosting.

Meta Blogging - This is for those things that everyone does. Someone posts some set of questions on one site, and then a lot of people will post the same thing on their site.

Review Sites - This is for reviewing the sites that reviewed your site.

Weblog Promotion - This is for any site that will help you promote your blog be it a blog specific search engine or an exchange of some sorts.