Weather Underground – Local Weather Conditions
Skyvector – Sectional Reference. (Not for flying, so still get your FAA
approved charts.)
AOPA Online – Aircraft Owners and Pilots Association
The Great Circle Mapper – Navigational Aid
Exams4Pilots – Practice Tests and Educational Materials

Cross Country Planning Tools:

Winds Aloft Information
E6B Emulator
Time, Speed and Distance Calculators