I've done a lot of research regarding this matter and I hope I can help.
Good old Macromedia used to market Flash Paper, which was supposed to be a PDF Adobe Reader killer as it allowed any webmaster to embed and display PDF docs online using Flash. But that was before they sold out to Adobe and Flash Paper was soon put on a shelf and forgotten in favor of Adobe's priorities.
However, Today there are a so many ground-breaking alternatives...
As a user has mentioned above you can use Scribd.com (the wanna-be YouTube for documents). But they're not the only service (and certainly not the ones most ahead of the curve).
Here are my two favorites:
- Issuu (http://www.issuu.com) or simply issue.com
- Mygazines (http://www.mygazines.com/)
I enjoy Mygazines's flash user interface the most (it's also faster) but it costs $99. It's pretty impressive. Depending on what you want to do that price tag can be worth it.
Issuu however, has won me over recently with their Smartlook Platform: http://issuu.com/smartlook
Here's a sample of Smartlook setup on a website:
http://www.ismartlook.com/
Plus it's completely free, which is nice.
A third alternative, which I've considered using myself is this free and open source code made by this guy named samurajdata. He calls it psview (PostScript Viewer). Anyone can download the source code and see it in action here:
http://view.samurajdata.se/
The converted PDFs losses quality as it converts to image fie, but it's fast and easy to setup.
I hope this helps!