Extend exhuberant ctags (the version in SVN trunk) to output function calls. You don't need to support vim,yacc,vera,html,or BETA only C/C++/C#/Cobol/Eiffel/Erlang/Fortran/Lisp/Lua/Pascal/Perl/PHP/Rexx/Ruby/Scheme/TCL need to be supported (although if you can support Java that would be a plus).