There are dozens of exchanges where you can get "cash money" for Bitcoins. Lately, the buy side (the people with cash money wanting to buy Bitcoin) is much more active than the sell side, which is why it's been climbing. In the US there's Coinbase and CampBX. Worldwide, there's Mt Gox (probably the largest, and, I believe, the oldest), and a whole lot of others. But, to get US dollars deposited into a US bank account, I'm using Coinbase.

People entering the bitcoin game generally put money into it. That money must go somewhere.

There are companies which accept bitcoins, for instance Foodler lets you pay with bitcoins.