Why try it: If you hate the idea of forcing your bridesmaids to all buy a traditional bridesmaid dress that they won't wear again, but you still love the idea of everyone matching.
How to make it happen: Pick a color, but be aware that perfect matches are going to be hard to find. Just be clear about the general shade, or else you may get variations on blue or beige that you'd never considered before. (Note: the easiest color to get right without having to micromanage with swatches is black.)
Although this is a great opportunity for your bridesmaids to find dresses they actually like, give them some parameters, like with hemline or fabric. If you don't want lace or are hoping for glitzy embellishments, tell them. If satin isn't your thing, let them know up front. If you feel stressed about all that freedom, ask that they send you a photo of the dress they've picked to get your final approval.