Buy and Sell Bitcoins

Coin.mx lets you easily buy and sell Bitcoin!

Mt.Gox is the largest Bitcoin exchange, located in Japan on its way out. Money goes in but it doesn't come out.

CoinLab and Silicon Valley Bank in California have teamed up with Mt.Gox to have a full US presence. The idea of a bank actually dealing with Bitcoin is exciting. This should raise confidence in Bitcoin!

Coinbase allows you to buy and sell bitcoin by linking a US bank account. It's easy to set up and link and the transfer times are average for an online bank transfer. Their fees are pretty low.

Bitinstant is great for cash deposits and very quick transactions.
Update: BitInstant CEO Charlie Shrem Arrested in Silk Road Bitcoin Bust

BitStamp lets you buy and sell Bitcoins.

BitPay is an online shopping cart solution for accepting payments in Bitcoin.

Bitboin lets you buy Bitcoin with Paypal or credit card, which is convenient, but they charge a very high premium.

LocalBitcoins is a place to buy and sell Bitcoins locally!

At CoinMama you can buy Bitcoins and Litecoins.