- First, there are no self-destroying archives and probably wont be in near future.
- Second there will never be 100% protection against anything people can see.
A quite commen tool to protect documents is Adobe Acrobat. Unfortunately today it takes less then 5 minutes to find a tutorial howto crack a password/ or copy protected pdf-file. In opposite to that, it is still quite harder to break an flash-based application-server common document- and presentacion services are using. Docstoc exclaimed in an interview, that they are secure enough to share private information like even business plans. Basically private functions are very likely to get the standard among document sharing plattforms like scribd, slideshare, sliderocket just to mention the most important players in this days. these platforms also offer password protection service, that allow you to track exactly who and at what time documents where opened. Best of all, those services until now are mainly free and sometimes also allow to sale digital documents.
So feel free to register at the services mentioned above for free, play a little bit around, evaluate their size to get an idea, who would have bigger damage in case of failure and just make documents available to your target group the timeslot access is required.