> I used this in some links, <a rel="nofollow" href="...">
> but the linked pages are still crawled, what I'm doing wrong? 

Nothing. The rel="nofollow" is mainly used for search engines, and its purpose
is not to allow bog/forum spam (it is used in this forum for all links, for
example).

Hence, web archivers such as httrack are generally not taking it in account.