You will need to swipe your credit/debit card, but will not be charged unless you return it late (after 9pm the next night). In that case, you'd pay $1/day for each day it's late.
You can check the Blockbuster Express website for locations and to reserve online with a code if you'd like to!
Here are a couple free codes that may work for you as well. You can use each code once per credit/debit card. The codes may or may not work based on locations (let us know in the comments if they work for you!):
R2G1 Free Rental Code: GRTWEEK (exp. 2/20/11)
FREE Rental Code: MRC37H (exp. 2/25/11)
(thanks Coupon Dad!)
Also, be sure to check out our list of Redbox FREE rental codes HERE!