#bitcoin-otc is an over-the-counter marketplace for trading with bitcoin. The marketplace is located in #bitcoin-otc channel on the freenode IRC network. If you don't have an IRC client, click here to visit the channel with your web browser.
#bitcoin-otc is merely an aggregator of outstanding supply and demand. All transactions that may occur are conducted directly between counterparties, without any participation or intermediation from #bitcoin-otc. As such, it is each individual's responsibility to conduct due diligence on their counterparties, and otherwise act in a prudent way to avoid falling prey to fraudulent users. It is strongly recommended that all users review the guide to using #bitcoin-otc, which contains a non-exhaustive list of suggestions for safe conduct on #bitcoin-otc.
The OTC web of trust is not foolproof. Do not rely on the ratings blindly - since the cost of entry into the web of trust is only one positive rating, it is not impossible for a scammer to infiltrate the system, and then create a bunch of bogus accounts who all inter-rate each other. Talk to people on #bitcoin-otc first, make sure they are familiar with the person you're about to trade with, have traded with him successfully in the past, etc.