That's funny, I have a very similar website (in terms of idea and a few functions) that's been on the background (never continued development) for quite some time. I like your ideas and structure as well.
Have you worked a bit on the calendar system? Gallery? etc. Work on certain pages like usercp and what not in order to reflect a more familiar system? The index is a great use of vba, "splash page" is not so bad (considering it's a splash page

) The forums may use just a bit of work in terms of the forumbit.
It's a great start but as I went and saw about 1-2 people online, it isn't the easiest to promote. What marketing techniques did you have in mind if you don't mind my asking?