INO.com - Specializes in options and futures information. Includes quotes, charts, news and market reports.
Ivolatility.com - Historical and implied volatility for options and equity derivatives. Tools for analysis and trading. Membership required for certain features.
Nothing But Options - Ran by an investment club with a passion for options, easy to understand tutorials, reviews and resources. Daily covered call watchlist and quotes.
The Option Club - Research and option strategies for equity, indices and futures. Membership required for certain features.
OptionMetrics - Research for individual investors. Intra-day quotes, analysis, implied volatility, strategies, and tutorials.
Options Clearing Corporation - The largest clearing organization of financial derivatives instruments. Contains options data, calendars and publications.
Taking Care of Business with Doctor J - Options trading resources featuring Jon "Doctor J" Najarian. Contains tutorials, educational content, market data and research. Registration required for certain features.
Yahoo! Options Center - Many resources for options investors including forums, quotes, tutorials, and strategy guides.