XREF v3.1 <ASP> - (formally C xref) 
cross-references any number of C 
modules and outputs: 1) A list of their 
global variables and constants. 2) A 
summary listing of the functions. 3) A 
verbose list of the functions. 4) A 
tree of the function's calls and 
callers.
From DA Software. Shareware.