Unfortunately, there isn't a site where you can design a dress and then have them custom make it that way, wouldn't that be cool? (If anyone knows of a site like this, please contact me!)
I love the Wedding Dress Creator site because you can not only pick necklines, sleeves, etc, but they have several hair color and skin tone options too.
This one is a bridesmaid dress designer, but the dresses come in ivory and white and could be a really affordable wedding dress! Check out Bridesmaid Dress Designer to play around with dress styles.
Other sites are good for browsing actual dress photos after you drill down your search features. You can search for silhouettes, necklines, sleeve type, designer and even price range and then view dresses that fit your search criteria. Sites like Dressfinder on Brides.com and Bride Couture's Dress Gallery are sites you should be sure to browse along with the two big ones I'm sure you know about, the knot and of course the Wedding Channel's dress gallery section. While this isn't exactly letting you design your own wedding dress online you are still able to see very specific styles. The plus side is that you are viewing actual dresses.
