No report spam method built in for non moderators. Only moderators and admin have access to marking as spam, deleting posts. We try to keep on top of it by checking the RSS feeds. A report spam button would also require some sort of report as well for moderators and for them to be notified.
If moderators were to remove the links from these posts, while leaving the URLs as clear text, then it might deter the spammers from coming back, without the risk of deleting a genuine post. Less work for moderators in the long run and everyone is happy, except the spammers.