It's quite interesting to see the differences among your directories. That shows how each directory is growing differently. I always thought computer or internt related categories are 2nd most popular ones, and they are very popular ones in many of your directories, too. I also noticed many finance and health websites often find your directory.
I was gonna say reference category is one of dead ones! Are you sure you have checked those sites, and they go under that?
heh, not like homomojo.com which is on page 2 of the seo contest. I think vacation is becoming one of the most popular categories everywhere as well.