Here's the method I use to manage website passwords: For logins that I don't really care about that much, say last.fm, I use my standard medium-strength 6 character password with a number and a capital letter, something like jfi3Jo. I can remember it because I use it often. For logins that I do care about like my email or bank I salt my base password by inserting three characters from the site's domain name into the front, middle and end of the base password. For example, my login to Hacker News would be yjfic3Joo, where yco from ycombinator.com is added in the front middle and end of the base password.

I know it's not the most secure method in the world but I think it is a good compromise between remembering the passwords and providing a unique-per-site decent strength 9 character password. If someone figured out my scheme they could get into all my accounts but in order to figure out my scheme they would have to brute force crack two of my 9 character passwords from hashes from two different sites and then match up the two accounts and compare the differences, that is the risk I currently take.