Bitcoin - Payment network uses peer-to-peer technology to operate with no central authority or banks.

Bitcoin Foundation - standardizes, protects and promotes the use of Bitcoin cryptographic money for the benefit of users

Bitcoin Investment Trust - private, open-ended trust that is invested exclusively in Bitcoin and derives its value solely from the price of Bitcoin

Bitcoin Talk - general discussion about the Bitcoin ecosystem

Bitcoin Wiki - site offers background information on Bitcoin, including best practices for traders, technical articles, marketing resources and more

Bitcoin Wisdom - Bitcoin/Litecoin charts with EMA, MACD and other indicators

Bitcoin.de - Bitcoin marketplace to buy, sell and trade, also offers news

Bitcoin100 - aims to convince new charities to start accepting Bitcoin donations

Bitcoincharts - provides financial and technical data related to the Bitcoin network

Bitcoins.com - provides information to help understand Bitcoin

Bitnodes - estimates the size of the Bitcoin network by finding all the reachable nodes in the network

Coinbase - provides a bitcoin wallet and platform for merchants and consumers to transact with the digital currency

Coinsetter - NYC-based forex trading platform for Bitcoin

PaymentsSource.com - Delivers news and information on the payments industry, offering editorial features, data and industry rankings, research tools, and more.

Physical Bitcoins by Casascius - offers Bitcoins as physical coins

PREEV - site displays the Bitcoin exchange rate

TREZOR - offers a hardware Bitcoin wallet

useBitcoins.info - offers a directory to search places that accept Bitcoin

yBitcoin - free print and digital guide to the Bitcoin ecosystem showcasing the best of Bitcoin to a global audience of businesses, financial leaders, investors and enthusiasts