Optimal? No. More than sufficient? Yes. You can use all numbers in your password, so long as it's long enough (and the website actually uses all of them).
I use a hashing bookmarklet myself. Only, I wish there was a better algorithm and I think it's wise, at least with an audience like HN, to point the weaknesses of those system. See for instance : http://stackoverflow.com/questions/554224/is-the-bookmarklet...
