My friends wedding I was in, we all wore black heels, but two of us switched to flip flops for the reception.
A sisters wedding I went to, she actually had her bridesmaids go barefoot for the ceremony (which I actually felt bad for them because it was outdoors, in March (which it can still be chilly in March in AZ) and they were walking on concrete, which keeps in the cold or the heat). She wore flip flops (the rocket dog type). The only reason I knew she had flip flops on was her dress was to long and she actually had to lift it to walk down the aisle (I'm suprised she didn't get it hemmed).
When I get married, I've debated flip flops, I've seen the ones I like in a bridal magazine.
http://www.bellissimabridalshoes.com/
I figure it's my day and I might as well be comfortable. I love wearing heels but they KILL my feet within 30 minutes to an hour.
I love these Vera Wang shoes, but there is NO WAY I can justify $395 for a pair of shoes.