Rod Machado’s Aviation Learning Center - Fantastic resource for pilots to learn the basics and study more advanced topics.

Aviation Weather - Great site for weather forecasts - you can even get current conditions at several airports (METAR), national satelite an radar images.

AirNav - Provides free detailed aeronautical information on airports and navigational aids in the USA. (Suggested by Eric Poole - thanks!).

Aircraft Owners and Pilots Association - A great resource for members as well as non-members and student pilots.

ForeFlight -  The essential app for aviation.

Avemco - Offers renter's insurance. Required by Eagle East Aviation.

Skyvector.com - A comprehensive flight planning tool on the web.