Here's an article on remote queries: queries that go against tables (or queries!) in other databases. It sounds really powerful.
That's one of the things I like about Access- just when you think you're getting a handle on the breadth of what it can do you find out about a whole new topic.
"This article discusses one of those hidden gems that I discovered when investigating Access Automation. Whilst looking into that technology, I stumbled across a SQL help topic in Access that described an extension that allows you to point your current query to a table in another database. This in itself didn't seem all that interesting because I had been doing this for years using Linked tables. Then I noticed that you could also point your local query to a query that was in another Access database. No links, no local query definitions, this was starting to get interesting."