Save America's Postal Service is a website dedicated to just that! There will be rallys held on September 27th in multiple congressional districts. There are some petitions you can print out and have people sign..OR..you can do what I did..sign the online petition.
To do so, click the link here and then fill out your information. You can also read about the proposal on the site as well.
If something so small could save the Postal Service wouldn't you do it?