I would second the recommendation of the Spinervals. I am just getting back into cycling and generally ride 10-20 mile rides on wknds, but can't get out much during the week. I recently purchased a LeMond Revmaster to use for indoor training and have been using the Spinervals. I think they are a pretty good workout -- not like riding for real, but much better than nothing. I also bought the DVD set from the 2003 Tour de France, and I use this also for some variety.
As for your original question, when I was looking into DVDs I did find several sites that offered "virtual" rides. I thought the best was
www.bike-o-vision.com . I have not purcased any yet, but I may if I get bored with my current dvds