The Olympic green was made for the 2008 Summer Olympics, and remains an important tourist attraction.
The Olympic Park in Beijing is accessible on line 8 of the subway. There you can walk around and take photos of the iconic stadiums. You may enter the stadiums for a fee as well, if you care to.
Since it's such a wide open place, they have a lot of people there selling kites; the ones they had when I was there used a series of mini-paper kites tied in a row, so that it was very easy to fly the kites (some guys had a one on each finger, and there wasn't much wind). They have some tourist kiosks (see below) but I recommend buy directly from one of the guys on the pavillion; you can get one for 1 or 2 kuai, depending on your negotiation skills.
One of the funniest things that happens to westerners in China is that people want to take photos with you. I try to enjoy it and just let it happen; after all it doesn't really hurt, right? On the olympic green, there are tons of tourists from all around China, many of whom are from smaller towns that probably don't see too many white people. So on the Olympic Green we ran into about 10 different people who wanted to take photos with us.
Now, a standard heat releasing technique in China is to expose the midriff by pulling your t-shirt up. I desperately wanted to get a photo with someone doing this, and saw my opportunity:
Unfortunately when we posed to get our photo taken, my friend pulled down his shirt, so I look like the relaxed, northern Chinese guy, and he like the foreign tourist:
Oh well, lost opportunities... So the trip continues: