http://www.realestateshows.comThey are excellent, unlimited tours for $129 a year (can not beat it, I use it for more than just virtual tours of houses) There is an option for it to be automatically posted to Trulia, Zillow, and Googlebase.
The "tour" itself is only 9 pictures, but you can add as many additional pictures as you want, plus you can add lots of information about the property and community.
It's the best thing I've seen for economy, quality, flexibility, and usability.