SURBL has added a report of Most Abused TLDs. This is a daily count of the TLDs most commonly appearing in SURBL data and is an indication of relative abuse levels.
http://www.surbl.org/tld-subtotals.head
The TLD .cn is disproportionately represented, most likely due to persistent and widespread abuse by the "Canadian Pharmacy" botnet-using spam gang.
http://www.spamhaus.org/rokso/listing.lasso?-op=cn&spammer=Canadian%20Ph...