If you're tired of Adobe's bloated Reader software then you'll find jPDFViewer a breath of fresh air.
It's designed mainly however for developers that are working with Java applications and wish to insert a simple PDF reader within them. In this way, you can allow users to view PDF documents without the need to install a third party application.
Because it's Java based, jPDFViewer works on all platforms. It can open PDF files on a local or network drive, from a URL and from an input stream for files that are generated in runtime or come from a database. You can print PDF files and it's easy to navigate supporting thumbnail, bookmark and annotation views.
However, jPDFViewer has clearly been directly translated from Windows onto Mac and the result is a Windows style interface and installation process which doesn't look great on a Mac.
For those that don't want to be dragged down by Adobe Reader or install third party programs into their Java applets, this is the perfect solution.