I have a client (a chiropractor) who has some audio links on a website I am developing for him. He only wants them available for downloading to people that are in the 778xx zip code area (basically he knows that if they are out of state, won't be interested in his services, so the zip code will weed out people that are not viable clients).
He wants a small registration box placed under the teaser audio clips for a person to complete if they want to access the complete audio clip. The registration box will ask for 1st name, last name, e-mail and zip code. He would then like the info collected e-mailed to him for his records.
If the zip code starts with 778, then they would be taken to a page with the complete file for them to download then and there.
If the zip code starts with something different, then he wants a message to pop up that says something like "your request is being processed" and then an e-mail is sent to him with the out of state request. He then would contact them via their e-mail giving them a password where they can access the page with the full audio clip if he feels they are viable candidates.
Either way, he wants to collect their registration info, but he doesn't want out of state people to have instant access to the link.
I don't think security is a big issue with this, more of a weeding out process.