1. Do something creative so they know you're creative.
2. Let your work speak for itself.
Normally, I recommend the latter (that's #2). I think it's better to spend your time coming up with great ideas you can put in your book than working on clever ways to introduce yourself. I've also seen very, very few students successfully pull off the former (that's #1).
This, however, is someone who got it right. Great idea. And because she's looking for a gig in account services, it's even more impressive/necessary. (And it doesn't hurt that her idea was picked up by Adweek.)