another point loki, a 'portal' is kinda just a big branding exercise, so pull in EVERY resource you can think of for branding your central site.
eg:
http://www.purve.com/store.html
I've never sold ANY cafe press items, probably rarely will ... but fuck the thumbs look professional and make my site look like it has an awesome store!!! LOL
your portal can have as many sub categories and sub domains as you can find content to fill it ...