General XC skiing 

• xcskiworld.com -- official website of AXCS 
   

• Discussion groups
   

• National XC Ski Education Foundation 
   

• Australian Ski Instructor Manual -- lots of hints and exercises for beginners and intermediates -- but targeted for instructors, who are assumed to already know the techniques.
   

Racing Techniques + Training 

• rec.skiing.nordic newsgroup | archives

• The Master Skier -- magazine  
• Janne G's website  
• SkiPost  

• National Cross Country Ski Education Foundation -- NCCSEF  
• FasterSkier -- Torbjorn Karlsen is a well-known coach in USA  
• skifaster.net 
• Stephen Seiler on performance, physiology, training  
• Silent Sports -- magazine -- upper Mid-West U.S. focus  
• SkinnySki.com -- Adelsman's page -- Minnesota + upper Mid-West focus  
• Alaska Pacific University Nordic Ski Center

see also 

• Resources for learning Classic ski technique 
   
• Resources for learning ski Skating 
   
• Places for XC skiing