That's my right hand in Sean's picture, and my buddy Matt came up with the idea. We inevitably had to remind each other to add 'Bless' (or whatever...but for us it as usually 'Bless'), so we would make a folded-over index card sign and put it out on the battle mat. The running joke became "The Bless Lamp is lit!"
I run the cleric in our home games ('Kingmaker', currently) and am running a cleric at Pathfinder Society. So on the first day of GenCon, he presents me with an actual "Bless Lamp" :)
I don't want to give away his trade secrets, but it's pretty simple. It's one of those little battery-powered LED sticky lights (like you see advertised on TV to put in a closet or anyplace you don't have power outlets). They're really cheap (like $1).
He put some colored cellophane under the plastic some (it dissembles very easily), mostly to cut the glare (the unshielded LED lights are crazy bright in the context of a gaming table). The color is kind of a happy accident.
And Sean, you should know that my friend Matt was all smiles when you came buy our table and took a picture of the light. We're all big fans, and he was super geeked that you thought it was neat :)
