The second law of thermodynamics and the first law of Nelly lyrics hold that ambient heat and clothing have an inverse relationship. Disturb the natural order with today's Groupon: for $45, you get $100 worth of designer dress and accessory rentals from Rent the Runway, redeemable online. Rent the Runway has received a slew of positive press, including recognition as One of the Best 50 Websites of 2010 from Time magazine.

Rent the Runway is an online haven populated by beautiful designer dresses and accessories waiting to be rented by fashion-forward women who dare to experiment with new brands but don't want to commit to buying a piece. Rent the Runway carries more than 100 designers' wares, and the way it works begins with you rifling through a virtual Versailles of fashion organized by date, occasion, style, or designer until you stumble across the Chosen One—the garment foretold in legend that that will fulfill fantasies of fairytale love and transform former friends-with-benefits into former friends-with-regrets. Be the designated belle of the ball in a Badgley Mischka Heavenly Halter Gown (rental $100; retail $700), or stop Segway traffic in Haute Hippie's Little Miss Vixen Dress (rental $75; retail $695). A venerable variety of accessories ($10–$65) can also be added, including headbands, bracelets, and necklaces. Book your completed look for your desired dates, and Rent the Runway will send the show-stopping ensemble to your doorstep along with an extra size for no charge to ensure the ideal fit. Rentals are for four or eight days, and once you've wowed the crowd at the annual Star Trek convention's formal gala, simply send the garment back in the pre-paid envelope provided.

Two Harvard Business School students began Rent the Runway to solve one of life's eternal paradoxes—having a closet full of clothes with nothing to wear. Fall brings plenty of occasions to show off your killer sense of style, so seek out a designer outfit for your next wedding, holiday party, or pet gerbil funeral anniversary.

Valid for those who have never made a RTR purchase. Valid toward $5 insurance charge to cover dress or accessory damage.

Reviews

Rent the Runway has been featured in several national press outlets and was named one of the 50 Best Websites of 2010 by Time:

• The site can help you be that girl who never wears the same dress twice. – Staff, Time