My first try (on August 23) was to mark some game notes private. When I did this, I could only read those notes when I logged in to the ralph_dnd account. That was unsatisfcatory. (Trying to edit or delete those notes was even worse, since I could only find them with the ralph_dnd account, but I could only edit them with the ralphmelton account.)
My second try, late at night on August 27, was to set up a custom group of friends that was included me and some other friends who were not playing in this campaign. I downloaded the LiveJournal client to set custom groups, and went ahead. I thought this was kind of a cool idea, because I could share my secrets with folks like Willie and Sara, but avoid sharing them with the players.
It worked better, in that I could see my secret posts as ralphmelton, but mike couldn't see those posts, and neither could I when I wasn't logged in. But Sara could not see those posts. Oh well; I had a solution that was at least satisfactory.
I just tried to post a secret in this way, and the LiveJournal client told me, "Sorry, you can't use custom groups on shared journals." Fooey.