Last month we broke down how the rapidly growing site RentTheRunway.com works, but for those who missed it, here's a quick refresher.

The members-only website, founded by Harvard Business School grads Jennifer Hyman and Jennifer Fleiss, rents out high-end designer merchandise and accessories for a fraction of the retail prices.

For example, a $1,900 cocktail dress by "Project Runway" alum Christian Siriano rents for $200, while a $2,250 Proenza Schouler schoolgirl dress can be rented for $250. Other apparel rentals start as low as $50 and accessories at $10.

Now those prices have dipped even lower thanks to the site's big summer sale, which runs today through Labor Day and offers rental goods from the likes of Matthew Williamson, Prabal Gurung, Catherine Malandrino, Helmut Lang, and Hervé Léger starting at just $35. And that's not all the start-up has going on.

"This week we launched three exciting new features on Rent the Runway," Fleiss tells StyleList. "The first is our Real Runway Moments page, where customers have the opportunity to upload video testimonials and quotes about why they love renting the runway.

"The second is product reviews. Each dress and accessory now has a reviews tab, where customers can add feedback such as how the dress fit, what the fabric and color is like in person, and if they'd recommend the dress to others.

"Lastly, we've added a Tell a Friend link so customers can recommend dresses for their girlfriends by quickly sending an email with an image of the dress or accessory."

For first-time visitors to the site (membership is free!), Hyman explains what type of merchandise to expect.

"We typically buy very editorial pieces that women will be less likely to buy [themselves]," she says. "Our team of buyers purchase from designers like any department store would. We pick dresses from current season inventory, and we also actively engage our customers in making selections by listening to their requests and preferences."

As for the duo's own preferences, Hyman says she's eyeing the new styles from Preen. "They are super sexy and beg a second -- or third -- look!" she says. "And I'm obsessed with the Proenza Schouler Kaleidoscope cut-out dress. It's sophisticated with an edge."

Fleiss, on the other hand, is all about the Lela Rose sparkle halter frock.

"It's pretty, classic, and great for summer," she says. "Such a fun style to rent because it is so memorable!"

Want more online shopping updates? Keep clicking to read about the launch of The Row's first e-commerce boutique.