Being newly engaged, I have started to prepare for my wedding, and just chose my bridal party. I really wanted to send my now-bridesmaids "Will You Be My Bridesmaid?" E Cards, but I had a really hard time finding them. I finally found this site: paperlesspost.com.
I was able to create my own invitation with a pretty design. You use "coins" to send these E Cards, and if you intend to use this site regularly, you will need to purchase these coins. However, when you sign up for the site, you receive 25 coins for free. I was able to send cards to all 6 of my bridesmaids without having to pay for anything!
I hope this helps anyone looking for the same thing! Good luck!