Bitcoin Tor workers

Tor is a distributed 'onion' network, that makes it more difficult for an adversary to track any one peer on the network. Tor also is very useful to access the 'uncensored' internet in countries such as China and Iran. Preserving privacy means not only hiding the content of messages, but also hiding who is talking to whom (traffic analysis). Tor provides anonymous connections that are strongly resistant to both eavesdropping and traffic analysis.

Bitcoin can run easily on the Tor network.

todo explain: onion routing (how tor network helps to anonymize), encryption used, exit nodes, routers

Please follow the instructions provided with installation files and read the list of warnings. Tor doesn't magically anonymize all your traffic just because you install it.
Down the page you can find examples how to configure applications to use Tor to anonymize the origin of your traffic.
This is a detailed installation guide for Windows. Before you setup Bitcoin or mIRC to use Tor, please install Tor and start in.
On the taskbar of your compute you'll see a small green onion when Tor is running.

Once you have your Tor client up & running, you can configure your Bitcoin client to use it.
Select in menu Settings -> Options

Check "Connect through socks 4 proxy" with the address 127.0.0.1 and port 9050 (the Tor default port number)
Configuring an application to use Tor is also called to torify it. (needs a brief howto here)

the note about bitcoin-otc promote on a more appropriate place in this page? reference to trading and IRC Conducting business using bitcoin-otc can be done more anonymously when directly connected to a Freenode IRC hidden service.

Run bitcoind with -proxy=127.0.0.1:9050 (or whatever your SocksPort is).

bitcoind will detect that you are using a proxy on 9050 and will force the "nolisten" flag. If you are not running tor on 9050, you need to set "nolisten" manually otherwise you will listen on your public IP and possibly reveal that you are running a node.