banana republic, you already knew this!
jcrew, martinandosa, anntaylorloft
BR and JCrew are quite pricy, Ann Taylor is strictly women's clothing...
As someone who has done a quite a bit of online shopping here are some tips:
-Make sure you read the return policy, it's a pain in the ass to mail something back to the manufacturer, so if you order something from, Urban Outfitters, check and see if it's possible for you to return the goods at an in-store location. Most stores allow this.
-Do a quick Google check for online coupon codes for you to enter when you check out. Usually you can find one for at least 10% or free shipping to save you a couple bucks.
-Do your best to stick with reputable sites. I buy my clothes online directly from the clothing store's website (i.e. Banana Republic = bananarepublic.com) since there are a lot of scams out there just check and make sure that you're entering your CC info on a valid site.
-Make sure you find your fit. Each store has it's own definition of XS/S/M/L/XL/etc., so try and find an in-store location ahead of time to get a feel of how they fit their clothes.
Other than that have fun shopping! I always check my favorite stores online websites to see if they're having any sales for me to get cheap clothes, but I'm in no rush to expand my wardrobe since I've already spent way more than necessary on what's already in my closet >_<