Shortlist of ski manufacturers who also made tennis racquets:

• Head
  
• Kneissl
  
• Fischer
  
• Völkl
  
• Erbacher (produced their own line of composite frames in Germany, plus all of the Dunlop frames "Made in West Germany")
  
• Rossignol
  
• Yamaha (who made knitting machines, musical instruments, and motorcycles before diversifying into sporting goods and stereo equipment)
  
• Elan (a FREAKIN' HUGE ski company in the small country of Slovenia reportedly made a few racquets)
  
• Hexcel (made a few tennis racquet prototypes, before returning to skis and composites R&D)
  
• Lange (a ski boot manufacturer reportedly made a few racquets)
  
• Spalding In the 70s skis were marketed under the Spalding brand. Most notable was the Sideral model was used by Gustavo Theoni.
  

Reference: http://tt.tennis-warehouse.com/index.php?threads/the-ski-club.548753/