Participate!
Edmund Burke once wrote, "all that is required for the triumph of evil is that good men do nothing."
Go door to door. Send an e-mail. Write a blog. Read, question and respond.
Sometimes, it's as easy as picking up the phone:
The White House Switchboard 202 456 1414
U.S. Senate 202 224 3121
U.S. House of Representatives 202 225 3121
ACLU National Office 212 549 2500