I used to keep all my passwords in Emacs w/ Org Mode. You can encrypt a heading, or an entire file, with a GPG key. This could work. Just store it in Dropbox/etc. If you trust Dropbox's encryption, just use a simple j.txt as manmukh says.

Or you could just email yourself, replying forever. That's pretty easy.

[link, almost forgot] http://orgmode.org/worg/org-tutorials/encrypting-files.html