I bought a bunch of pre-stamped postcards at the Post Office, addressed them to my representative (and left some blank for senators and local officials) and stuck on some of the mailing labels I get for being on every sucker list in America. Then, when I want to express an opinion, I just grab one and write "Please vote for Bill because" or "Thank you for voting for Bill because"--waiting for my computer to warm up is a good time for this, or as soon as I see something on the news.