I've been a member of the ACLU for a while and while I believe they are vital to our nation's future, I can't stand all the spam (snail mail) that I get from them; usually asking for more money. I understand that paying lots of lawyer's salaries gets expensive - but come on! I've already donated. Please don't ask for more money than I've donated (for an annual membership) more than once or twice per year! I hate to imagine just how much of my donation is going towards spamming people and filling landfills with wasted paper.
I went to the ACLU website to update my postal address and found out that you can ask not to receive postal mail.
After a few months I'll update this post to let you know how much spam I'm receiving.
UPDATE – 2008-09-10: They have removed the "do not send me postal mail" option. I continue to receive snail spam. :-( I have complained to membership services.