I'm trying to determine which categories would be appropriate to categorize products and services for webmasters into.

I'd like to have main categories with sub-categories inside them, and I don't want too many main categories, sub-categories can always be added, so don't pay too much attention to them.

Here's what I have so far, EVERYONE'S opinion is appreciated:

Bulletin Boards, Content Management, Ad Management, Help Desk, Statistics Tracking,

Books and Magazines
Promotion, Programming, Graphics,

Promotion Services
PPC Search Engines, Search Engines Positioning,

E-Commerce Services
Shopping Carts, Payment Systems,

Web Hosting, Domain Registration,

Graphics and Illustration, HTML Editors, FTP,

Freelance Services, Webmaster Resource Sites,

I like the categories for the most part, however I do not like the "Promotion Services" "E-Commerce Services" and "Services" I'd either like to combine those into 1 or 2 categories, or find better names.

Thanks for everyone's time,