WordPress site/s list

Hi,
I have been thinking for a while it would be pretty handy for many of us who use WordPress if there was a site where we could find a list of all the different ways in which WordPress can be used.
The reasons:
1. It would promote WordPress.
2. I would find it very handy myself.
3. It may be an easy way for us all to find a WordPress site when we are looking for one in particular.
I was just about to start this list when it occurred to me that you may have some useful ideas about the best manner to go about this process.
I am not a big fan of webrings so would prefer to not go down that road and anyway, there is already one in place [albeit, it is rarely ever open].
However, in order for the list to be functional it would need a bit of foresight before I begin.
What categories would be the most effective? Should I include a small description of each or allow users to add their own? Some initial ideas may be to list categories such as Scripts, Hacks and Plugins sites; Humorous sites; CSS sites, Personal sites, etc etc…
Is there a plugin or hack out there that would make it easy for a visitor to automatically add their site to the list? Should sites be moderated first – to avoid spam and additions from sites which have no place in the list?
May I just reiterate, I am doing this because ‘I’ would like a list which is easily accessible and can be regularly updated. Also, this is NOT a competition – it is just going to be a list with perhaps a small accompanying description – preferably written by the owner of the site – but if written by me – will be unbiased and factual – nothing more – nothing less.
Your suggestions would be much appreciated. Thanks 🙂