It's a good idea if one has an idea/enough content to get it going. I was thinking of something like a website based on countdowns.
Like, have a countdown timer for every upcoming game/movie/electronic device out there. Simple idea, but simple ideas tend to soar on the internet.
Just looking for a way to make a bit more money, as the expense of keeping the website up is pretty cheap, so you don't lose out on much trying.
I can give you some ideas M.Cizzle. I was fairly successful with adsense once before I got banned because I made a mistake!