The function keys (F1-F12) can be bound to functions in a similar
fashion as any other key.  

For example, you might set the following three function keys:

   (global-set-key [f1] 'mail)
   (global-set-key [f2] 'mh-rmail)
   (global-set-key [f3] 'discuss)

updated 4/15/00