Please let me know how I can do my part. If there is any way I can promote this site with ads, banners, etc I would be happ to add them to my site.
SE doesn't make specifically branded banners or such until a site graduates and gets its own theme. Right now we'll have too make our own banners/ads.
You can also find useful pieces of elevator pitch and such to describe the site on the About page.
You can see some ideas another beta site had with regards to a flyer to promote the site here.
As an after thought, we could have sort of a contest where users could design ads and post them on a meta post (sort of like Photography.SE's weekly photo contest). Other users would vote for the ads they like.
You can get your user "flair" on your profile. It's an HTML anchor and image that updates regularly. You can use it to "show-off" your reputation and badge achievements.