Ditto to Adam's post.

When I was still working retail / customer service, I created Access databases to track my supply orders and other items. I didn't need to do it for the job, but it helped me learn relational database structure and techniques that helped me transition to my first IT job.

Plus, even if your company doesn't use your DW, it's an item that you can put on your resume. Even if you say that you did it in a test lab, it's still legitimate experience. @=)