Network television using show's plot lines for cross promotion

I often don't watch network television. I prefer my specialty cable networks like Bravo, Travel Channel, Food Network, E!, and Comedy Central. One show that I do enjoy on network television is How I Met Your Mother. My group of friends is pretty into the show so a few weeks ago I gave in and became addicted to a sitcom. Besides the fact that Barney Stinson is Legen-wait for it-dary I've noticed a recurring trend throughout the four seasons of the show.

They seamlessly use plot lines to cross promote other CBS programs. The best example is the episode where Barney gets onto the Price is Right. As a child Barney was told Bob Barker was his father. Barney finally gets on the show and plans on telling Bob he's his son. Shot during Bob Barker's last year hosting, the show perfectly incorporates a completely believable Barney story line, while promoting and giving tribute to one of CBS's most beloved shows. I thought and talked about my love for the Price is Right for the next week, because of that episode.

As an advertiser, I'm curious to explore cross promotion more. As advertising moves more towards fitting into a consumer's life as opposed to interrupting it this style seems worth betting on as a successful solution for advertisers looking for different ways to promote their product/show/brand. Warning though: Tread lightly with this style. 30 Rock has recently been getting a lot of flack on the blogs for overdoing the product promotion to the point that it seems like bad ad copy as opposed to a plot line. How I Met Your Mother's cross promo style works because it fits seamlessly into the character's life. It has to be believable or the viewer will see right through the backroom deal between writers and advertisers.