The best I can find still is the 1000 mile offer:
Now through May 31, 2012, Dividend Miles members can earn 1,000 bonus miles on rentals of 3 or more days.
Offer valid on all car groups at participating airports in the U.S. and Canada.
Use coupon # MUAA017 and provide your Dividend Miles number at the time of reservation or at the rental counter to receive your bonus miles. These miles are in addition to the base miles you receive every time you rent with Avis.