I have some Extranet users. Each user has a dedicated page/item, that is maintained by the Admins. The Admins should manually be able to "connect"/reference the current item to a single extranet user. I am think of something like using a valuelookup type or similar on the template.
But how could i accomblish this, as the users are stored in ASP.NET membership, and not directly in Sitecore, as they were in previous versions of Sitecore.
I think you've got the right idea. Either store the users's full name (Domain\UserName) in the item, or store the item ID in the user's profile. If you go the Profile route, be sure and update Sitecore's User template in the Core DB so that you can see the value in the user manager.
There's also a Sitecore table you could use called IDTable which is normally used for mapping Sitecore item IDs to external data. That might be your best solution since user Profiles can be annoying... will also be the most efficient in terms of finding/indexing this data. Look at the Sitecore examples of importing data to get an example using this API.
