> I have someone in my company that wants to mirror some 
> sites to have them saved offline for future use. Can 
> HtTrack be used for commercial or corporate use?
Yes of course:
<http://www.httrack.com/html/faq.html#QG7>

Q: I use HTTrack for professional purpose. What about 
restrictions/license fee?A: HTTrack is covered by the GNU General Public
License 
(GPL). There is no restrictions using HTTrack for 
professional purpose, except if you develop a software 
which uses HTTrack components (parts of the source, or any 
other component). See the license.txt file for more 
information