Look at the right hand column to see the main ways of acquiring Bitcoin presently.
For a number of reasons the ease (or difficulty) of acquiring Bitcoin varies greatly depending mostly on where you live. There are a number of ways that you can acquire them and which of those is best for you to use depends alot on your own preferences and location.
LocalBitcoins.com provides a marketplace bulletin board (similar to BungeeBones Market Bulletin Board) where sellers and buyers can arrange to meet at a local place and time and conduct a transaction face to face and in-person.
Coinbase.com is probably the best (if not the only) option in the United States to purchase Bitcoin. You will need to provide your identification and bank info and the process may take a few days.
The Bitcoin Wiki is a good, up-to-date and maintained source of the current status of Bitcoin exchanges.
Google The Term "Bitcoin ATM and look for a Bitcoin ATM near you. This is a rapidly growing way to acquire Bitcoin and is growing too fast to provide an accurate list here.
Go To A Bitcoin Meetup Not only will you probably be able to find someone willing to sell you some Bitcoin but you'll probably learn alot, meet a lot of interesting people and have a great time doing it! Just do a search for "Bitcoin" at the Meetup.com website to locate the Meetup nearest you.