Many of the free resources available on the internet are sponsored by the Mormon Church (LDS) and many of the pay sites are owned/founded by members of the Church. Ray once asked me "what's in it for them?"
They believe that many of their ancestors weren't able to know the message of their Church. These ancestors are baptized by proxy into the Church. In other words, these people are baptized into the Mormon Church regardless of their religious beliefs. The Mormons believe that family ties are eternal and these ties can only be maintained if the ancestors are baptized.
We have occasionally come across a record on Ancestry.com where an LDS baptism has been recorded. Next time we find one, I will share it with you here.
The Mormons have come under fire this practice. At some point, many of the Holocaust victims were baptized by proxy. As you can imagine, this raised quite a stink. The Catholic Church has also raised concerned with the practice. The official LDS website now states that by baptism, the ancestors are given the opportunity to hear "the word" and then they can make a "choice".