I'm not sure exactly what we're looking for, but I'll take a stab at it to get the ball rolling...
Patio scene w/ Doug, Silas and Andy - Doug is smoking from a glass bong.
School Library - youngest son is selling "A cure for depression" to his English teacher.
Laundry room- While talking about a grow they mention Advanced Nutrients. Not sure this counts since it was spoken and not seen. Extra credit?
Living room scene near end of show- Silas is carrying a couple of tupperware
containers full of clones.
I was looking for product placement of 420 sponsors but I didn't really see any names.
This was the first time I've seen the show. It was pretty good. I laughed my a$$ off on the ransom bit. Now I've gotta rent the last 4 seasons on DVD.
Anyone else?