Here are some links toward very interesting sites for flight planning and meteorology:
SkyVector: Flight Planning / Aeronautical Charts: really thorough, useful for real and virtual flights. It includes the actual weather at each airport, navaids, calculation of distance and bearing toward your destination.
AWWS-Prévisions et observations: this is a section of the Nav Canada internet site, the company that manages air traffic services in Canada.
OurAirports: really thorough, offers lots of information about thousands of airports around the world.
http://www.airnav.com: especially if you are interested in american approach plates.
Flightradar24: real time air traffic, delays included and informations about the type of aircraft, the company name, etc.
LiveAtc.net: listen to live radio communications between air traffic control and pilots in many airports around the world. If you use this site with flightradar24, you will also be able to visualize the aircrafts movements.
FlightAware: a useful site for real time flight following. It also includes fresh aviation news and pictures.