I'd totally forgotten about this (and this). If you have own a domain and can create 'subdomains' which can point anywhere (ie: you are in control of your DNS) you should follow these instructions and have a go with directories. They're fun!
My brother could really use this for his WAP directory site, which gets shed loads of visitors every month and over 29 million clickthrus in total (wow!) on mobile phones. I built this with PHP and MySql.
If I could get these opml directories throwing out WML pages, and XHTML, or whateverML then I'll move him over to OPML. But then I suppose it's a matter of waiting for the server to be released.