So, you have a bunch of html that you want to include on both your vbulletin forum and your blog. And, I'd guess your blog uses no templates? I suppose you could write a php page to spit out that navbar in to a variable and then include the php page on your vb site and your blog and then spit out the variable which has all the html that the php page created. I've never tried that, but I don't see why it couldn't work. Actually, you may be able to put it all in a template and then just eval the template to a variable and spit it out.
I'd suggest just playing with it on a test site.
Oh, and I always blame everything on lack of coffee.