I'm working with SharePoint 2007 and we're currently working with another organization for a long-term project. We need to access documents in their SharePoint site.
After trying to figure out the wide array of Microsoft products branded with the name 'SharePoint', I'm not even certain that SharePoint can link to an external SharePoint site outside of the domain.
Is it possible to link two separate SharePoint sites together? If so, how is it done? If not, is it possible to program a SharePoint webpart or some .NET component to transfer documents from site A to B?
There are a few ways to do it but from what details you've given, I'd suggest implementing ADFS at the sites. This should allow them to grant your account permissions to the site. If however all you need to do is access the docs (like a normal website) they can set up the site to allow anonymous access and you can post a link to it on your internal site.