Yeah I can.  Read more details here: [Baptisms for the dead](http://en.wikipedia.org/wiki/Baptism_for_the_dead#The_Church_of_Jesus_Christ_of_Latter-day_Saints)

Basically mormons love to do family history, because then they can go baptize dead people.  Like the founding fathers, hitler, and the jews who died in the holocaust. 

They believe that everyone must be baptized to get into heaven.  All 99.9% of the world who isn't mormon.  So they go into the temple starting at the age of 12 I believe, and are baptized as a proxy for people who have died.

The explanation eventually became something along the lines of, "our baptisms are just a gift, the recipient can still choose to accept or receive it in the spirit world.