Anyway, the people at Her Room have seemingly thought of it all.
Return Policy. The first thing I checked was their return policy. They are good about returns and also do "phone exchanges" in which they send you the new stuff right away and just refund you for the old stuff when they get it back from you. Also, because their return policy is good, you can order a few sizes if you're unsure and just return the stuff that didn't fit.
Product Reviews and Ratings. Their products are available for review by customers, so you can see what people are saying about what you're looking to buy and also sort products by star ratings.
Bounce Tests. This is truly unique and really stands out to me. The took 40 or so of their most popular sports bras and took a video of a woman wearing it and mimicking a jogging motion. This is a great way to compare effectiveness in sports bras.
So many sizes! Her Room carries 28A-56K. I'm quite sure your size is in there.
See It Under... There is an option to see the bra on a manikin with various shirt/blouse styles laid over in to see what parts of the bra might show under a V neck, boat neck, button up, etc.
Fit Guide. There is a fit guide, which are suggestions on sizing based on customer feedback. For example, if the band runs loose, they might advise you to try a tighter band size and larger cup size to get the proper fit. This helps you buy and helps them minimize returns and unsatisfied customers. There is also a customer service representative available for online chat to help you make fitting decisions in a hurry. Furthermore, there are product specific measurements listed. For example, if something claims to be "low rise", they will tell you what it really is in inches.
Pictures. All products come with a variety of pictures from different angles so you know what the back and front will look like on a real person.
Shipping. Orders $70 and up ship free.
PayPal. I'm a huge PayPal fan and they accept it.
All in all, I would recommend looking through their online store and see if anything appeals to you for your next lingerie buying experience.