What is the prayer roll at an LDS temple, and how is it used? Latter-day Saints sometimes talk about "putting a name on the prayer roll" at their local temple. This practice is mentioned in Church magazines and on LDS.org, but is never explained in detail.

What is the purpose of the prayer roll at an LDS temple, and how is it used? When did this tradition first come about?
A name is written down on a piece of paper by a patron, or office worker (if the name is called in), and placed in an envelope of sorts.  This is put on the alter during the prayer circle.   The words of the prayer is up to the officiator but generally speaking a generalized prayer that their needs will be met is said along with other things. 

We believe that putting a name on the "prayer roll" will enable that individual with greater blessings from Heaven based on their needs.

As for the tradition, I don't know, but I did learn some things from @Daniel's link.