It isn't against rules here to post other writing sites. I don't know about other boards' rules. As for advertising, I'm off college for the summer and the campus is too far away to get to w/ gas and all, but when classes start again I'll get some flyers going and that should be a boost. I know what you mean, it is slow going getting members. Trust me, I've been dealing with this frustration since forming the board.
I also put the site at the bottom of all my answers on yahoo!answers. It occassionally attracts a passerby, but not all join. I know there is the potential for growth but I need help getting the name out there.
Also, a website (not just a forum) with JAVA type manuscript editing options could be in the works, but the specifics of that are still very hush hush because it's only been speculated on. But I think that might attract more users as well than a forum might.
Thanks for doing your part, my brother has advertised a bit for us on his own forum and other than constantly plugging it I don't know what else to do.
P.S. I promise to get to your story this weekend! Sorry, I had to work the fourth for the newspaper. It really sucked. And I work tomorrow, but not all day and I do want to spend some down time here with my homies. Expect a response soon.