i love preview but i grew tired of not being able to browse through image folders, tried jview and xee, stayed with jview for the stripped down/processor friendly aspect and have been happy ever since. still use preview for pdfs (and functionality gripes aside it's a great app).

it's not feature-rich, but nothing beats it speed-wise for PDF files.

I definitely agree - Xee is better than Preview for viewing images.

One of Xee's main benefits is that when you zoom in and out of the image it intelligently resizes the window... I can't stand Preview's behaviour of keeping the window size the same and just zooming in and out of the image. It means you always have to manually resize the viewing window.

Also try Skim PDF Viewer for your PDFs. I find it loads faster plus has more features if you need them.

http://sourceforge.net/projects/skim-app

Not many know about the Slideshow feature in Preview.app, but it's pretty sweet. Try it out: open up a bunch of images (perhaps a folder) in Preview and then go to the View menu and select "Slideshow" (the keyboard shortcut is Shift-Command-F).

Once in there, you can fit the images to screen and add it to iPhoto, but the best part is the "Index Sheet" (This also has a keyboard shortcut -- "i"). This action makes preview a good lightweight alternative to iPhoto for browsing photos.

For Quicksilver fans, there is a Slideshow action plugin that makes this action accessible without entering Preview at all. Very useful.

"Since Tiger it won't open animated GIFs anymore. Shame on you."
You can still open annimated GIFs in Preview you just need to hit the drawer button to see the other frames and then click the gray arrow.

I think Xee (http://osx.iusethis.com/app/xee) is better than Preview for viewing images.

PDFView is better for reading PDFs: http://osx.iusethis.com/app/pdfview

"Since Tiger it won't open animated GIFs anymore. Shame on you."
You're right, that really pissed me off.

I can't live without it's ability to open .pdf files natively.