Did you know Punk & Disorderly, Peyton’s web site on One Tree Hill, actually exists?
Peyton used the site primarily in season one to share her artwork as well as her thoughts. Also through the site that you could “watch” her on the web cam. (Actually you still can. It’s kind of weird!)
There are other OTH sites, like RavensHoops.com and TreeHillHigh.com.
Making a legitimate site for fans was recently repeated on 90210, with Silver’s blog, The Vicious Circle.
Another example: a site jokingly mentioned on Dawson’s Creek–www.AnnoyingSister.com–used to redirect to their web site but no longer does.
Not sure if there are any others sites created for teen dramas that actually exist. Do you know of any?
TeenDramaWhore 
I just rewatched an episode of DC’s 3rd season and thought it would be fun to check out if annoyingsister.com really existed:P Anyways, I know about a website called “Demons, Demons, Demons” which ‘existed’ in ANGEL (Buffy’s spin off series)