If it's a production DBA role be sure to know the things that ps mentioned above, especially questions like:

Name the system databases? (don't forget on this on to mention the resource database in 2005 for extra credit)

How would you troubleshoot a slow running query/slow running server? (you can really go for it here as it's a bit of a general question so be sure to mention all the sql tools you can think of plus which part of windows you would use and which counters are best)

What jobs would you run for maintenance?

What is the difference between clusted and nonclustered index?

The list is endless, you'd better search on google, there are some sites with some quite good questions on.