PDFView is a lightweight Mac OS X application to display PDF files.

What does it offers more than Preview?

By default, the main window will open up maximized, and the zoom level will be automatically the highest possible to fit the document into your screen - so that documents will become finally readable. Especially valuable if you are using a small size screen.
PDFView supports a powerful full screen mode, and a innovative "presentation" mode, in which nothing is displayed but your document, not even scroll bars. This mode is designed with Beamer user in mind, but not restricted to them. Apple Remote support is also planned, in the future.
PDFView offers powerful integration with LaTeX:
it recognizes when the file is updated on disk and offers to reload it;
if you are using the PDFSync LaTeX package, you can switch back and forth between the document and the text editor; just Command-click on a point in the PDF to be taken to the corresponding LaTeX line in your editor (customizable in the preferences);
again, if you are using PDFSync, you can set up your editor to jump you to the appropriate page in the PDF (please refer to this page for instructions about it).
PDFView has a very nice magnification tool: just drag around the document to use it.
PDFView supports a useful miniature display.