I know that for quite some time now that I am in the habit of placing a 'fin' at the end of my fics when I put them on the message boards, and thus it would appear on the ones placed on the archives.
I've also seen other gentle writers use a finishing line such as 'TBC' or some such thing if the fic is going to have a sequel.
Tank (who is a creature of habit because it's easier)
