There's the PAD Kit from the ASP that you can get for free.
But, there are no free ones out there. There's an austrialian download site (http://www.downloadpipe.com/
) that sells it's script and DB, but it's around $4,000 or so. http://www.FileCart.com
also sells it's script for abot $2,500 or so. I've seen 1 or 2 others, but can't remember much about them... maybe I'm confusing them with the two I just mentioned.
The PAD stuff is a bit of a mess. If you check out any of the numerous PAD Kit sites, you'll see how amateur they are. The PAD Kit isn't a professional solution - it's a starter kit to kick-start your development.
I've been wanting to start a site for a while, but haven't gotten around to it as I'm working on other things at the moment. When I do get it done, I'm going to proabably offer it for around $2,500 or so or a co-branded version for much less. I haven't even started, so I have no idea what I'll do yet. I won't go the LAMP route as I personally have very little respect for a lot of the kinds of sites that use it (Linux Apache MySQL PHP). I'll go the ASP.NET route - more power, easier management, better technology. (Yes - I can be a bit of a techno bigot at times - though I do use MySQL and am not totally averse to LAMP.) I've already finished most of the data model, but it's a LOT more complex and robust than the PAD Kit model - good and bad things there of course in both cases. If you want I can send you the SQL to have a peek at. You'll need MS SQL Server or the MSDE and Enterprise manager to use it. It's about 70% complete - all the PAD stuff is there, but not the other site stuff, and it's missing stored procedures at the moment.
If you want a fast start, you can do the PAD Kit thing, but you'll need to create your own application to fill the database. This is proabably the most important thing. Also, you'll need to decide if you want to manually verify things. There are a few slimeballs out there that submit fake PADs and it's getting worse. There have been a few discussions in the ASP newsgroups about this.
I'd be interested in further discussion on this topic - I love datamodelling and building web sites when I have time.