In most weddings I've attended there has been a point in the service where the bride and the groom each take a candle (sometimes brought up by the mothers) and light one larger candle to signify their union. I always assumed that everyone did this and didn't give its origin or process much thought...
Until we were planning our wedding. There was much discussion on whether or not we would blow out our candles or leave them lit to say that we were still individuals even though we were coming together. It was important to Brian that we leave them lit, but then in the ceremony he forgot and blew his out. So if you watch our video you will see me pause and then blow mine out too.
Recently, Brian came home from work to tell me his co-worker believes that he and his wife invented the unity candle. If you search wikipedia it lists his story as the origin so it must be true. :) Here is a link to his blog that tells the entire story.
In the same week, we attended our good friends Steve and Brittany's wedding. They were the first couple I've seen that did not do a unity candle. Instead they had two vases of colored sand (brought up by their moms) which they poured into a larger vase. I think the intention was for the sand to mix, but Steve poured at a different rate than Brittany and ended up dumping the bulk of his on the top. To make up for the lack of mixture, he put his index finger in the vase and gave it a little twirl. It made me smile.