I have got my AD set up with Sharepoint 2010, but I need to display a list of all users in the AD as a list of contacts. How do I go about doing this?
Have you configured User Profile Sync to setup user profiles for your AD users or do you need to query AD directly? When you say you want to display a list of contacts, do you just want a page that displays something like a staff list, or do you really want contacts.
If you want real contacts (for outlook sync etc), then I agree with Wictor that BCS is the way to go.
If you have setup UPS and have user profiles in SharePoint for the users you want to display you have a few choices:
For my money, if you have UPS configured and just want a staff list kind of page, I would probably go with using the Search web parts and some custom XSLT.
You could create a custom connector/.NET connector for BCS and leverage AD as an external list. BCS also allows you to set the entities of the list as Contacts, which allows nice sync with Outlook (for instance).