I’m afraid the website backend software was hacked through a known exploit, causing great havoc and lots of spam links to be inserted into the site in random places. I have cleaned up the majority of the problems on the primary pages, and will address the rest soon. It will take some time, so please be patient.
In the meantime, if you notice anything wierd—in particular any spam links—please let us know.
[Update] I believe everything is back to normal now. If you see anything amiss, let us know. Thanks.