I actually have $30 a month budgeted towards entertainment, though looking back at the past few months I haven't been good at keeping to it on average. But it looks like the things that put me over budget were large, unusual purchases, like the fee to attend a high school reunion.
Most of the time Awayfarer and I don't spend much on entertainment stuff. We might spend a dollar a week on renting movies (yay for Redbox!). Sometimes, not often, we'll go see a movie in the theater which will probably come out to $20 or so for two people, including snacks. Every once and a while I'll buy a computer or DS game, usually not for more than $20.
It has been a looong time since I've had to spend any of my own money on books, D&D or otherwise. I have a membership to Barnes & Noble and also have a credit card that sends me a $25 gift certificate to B&N each time I spend $2500 on the card. I use my credit card for just about everything, so I wrack up these gift cards pretty fast, and I pay off my entire card balance each month so I never pay any interest on the card.