Free Rate Case Charts from the Postal Rate Commission website:
http://www.prc.gov/docs/48/48667/Att_A_-_Rate___Fee_Scheds.pdf
Extremely useful comparison charts from PostCom:
http://www.postcom.org/public/r2006/r2006.rate.charts.htm
note their warning regarding the caution that must be taken when trying to compare rates.
The USPS Rate Case information clearinghouse:
http://www.usps.com/ratecase/
Bookmark the USPS page for future reference, we will be monitoring it closely at this end.
Best wishes!
Lisa