Thanks for this thread about the categories widgets:
http://en.forums.wordpress.com/topic.php?id=13096&page&replies=12#post-100749
I was also confused about why there could be up to 9 of them but they have the same options.
On my blog (http://ratchasima.net) I want to use one set of categories for general topics and one set for the names of persons. Is there any way to do this other than the categories widgets? Like doing something tricky with a text widget?
It would be good if Word Press could give the option through the categories widgets, though.