Let's begin.

Cost of Entertainment
If you go to a movie theater to see the latest and greatest action movie, let's say you pay ~$15 for a 90 minutes movie. So that breaks down to about $0.17 per minute for your enjoyment.

That's a good baseline to use to begin comparing things.

How about the roommates and I going out to a hookah bar (Ziryab in San Francisco!) for a few hours on a nice Sunday afternoon? That's about $20 per person for 2 hours. Interestingly enough, that breaks down to about $0.17 per minute as well.

How about a random Friday night in the Mission? Let's say about $50 for 3.5 hours or so (which we know is probably a preposterously low estimate and is likely way more than this). That goes up to about $0.24 per minute. No big deal I guess.

So we've established a nice baseline for the prices we pay when we go out to enjoy ourselves. We'll go with a nice average and say our price / time ratio works out to ~$0.20 per minute. For fun, we'll name this ratio the "Fun Constant" or Fc.

Cost of Playstation 3
Let's look at how this relates to the PS3.

The newly acquired 40gb PS3 is $400. That's not factoring in games or anything like that. So to get that down to the magical $0.20 per minute, that means we need to utilize the PS3 for about 2000 minutes, or 33 hours. Nice!

Of course, factoring in games complicates matters. By themselves, it isn't bad though. A game is $60 (ridiculous). Which means that we need to play it for 5 hours before we get to our magical price / time ratio.

Equations
The real geekery comes when we try to figure out how these two separate entities work together (ie, what is the total entertainment value we get when we combine games with the PS3). There are going to be a bunch of variables to sort this out, but I believe in the end, we can come to a clean and beautiful solution.

Fc = price / time ratio
PS3(cost) = Price of PS3 ($400)
PS3(time) = Time of PS3 use in minutes
N = Game number (ie., Call of Duty 4 = 1, Uncharted: Drake's Fortune = 2)
Game(cost) = ($60)
Game(time) = Amount of time game has been played in minutes
N(total) = Total number of games

So let's put this equation together!

Fc = ( [PS3(cost)/PS3(time)] + [Game_N(cost)/Game_N(time)] + [...] + Game_N+1(cost)/Game_N+1(time)] ) / N(total)

So let's look at an example using two games: COD4 (game 1) and Uncharted (game 2).

Fc = [ (400/600) + (60/420) + (60/180) ] / 2

Fc = $0.38 per minute.

Obviously, this means one should keep on playing. ;)

Conclusion
So when people start complaining about how you are spending too much time playing video games, you now have a way to justify the excessive amount of time spent doing it: The more you play, the cheaper your gaming system gets!

-Dave