We are getting a number of spam answers. Suresh is deleting them quickly but that is not a permanent solution.
I think SE system should be more intelligent and doesn't allow those spam post in the first place. The structure of these spams are very similar, so it should be easy to disallow them, but I think a more permanent solution would be better. So I suggest that:
User's with reputation 1 should not be able to post answers containing links (possibly with the exception of a white list, say links in edu domain, arxiv, citeseer, springer, doi, ...).
We can analyze the links in the posts we have got so far and check the most linked sites and then exclude them.