Actually in the initial version there were many other classes but I decided to change the foundation of the NPC Gen so that almost everything in the system was script based and could be changed easily. Currently in the new scripted systems it can handle the following:
1. All SRD Races.
2. All SRD Spells, Skills, Feats, Weapons and Armor
3. Fighter and now Barbarian (Rogue is next and then will start moving to the rest)
4. Monster Races (Hill Giant for now but able to handle many more)
5. Templates (I have done Half Dragon, Half Fiend, Half Drow, Vampire)
6. Almost all SRD magic items that can be worn have been added.
7. Prestige Classes are coming.
If you wish to find out more, I have posted a lot of information on my website
www.rpgattitude.com. If you have any questions feel free to ask.