These generally take quite a bit of live play to qualify. They also tend to be done by rooms that aren't doing very well.
I know Harrah's has them sometimes. Rio has done them in the past. The Golden Nugget may have them. Treasure Island has free rolls, but not weekly, usually monthly.
It's actually not a great idea for a promotion, because you need to come back to the poker room at a specific time, and then you need to get very lucky. So there's probably not a huge number of people motivated by this. And the people who are motivated by this tend to be the douchebags, IMO, which makes the promotion even more unappealing.
Poker isn't doing well in the USA right now, due to the prohibition of online poker. The vast majority of tables in Las Vegas are idle.
