Originally posted by: jw0ollard
If you select multiple photos with your mouse, or Command-A to Select All, just double click on any one of them and it opens them all up in Preview.
Then you just use Up/Down on the keyboard to move through them.
Originally posted by: TheStu
Highlight all, right click on one of them and hit Slideshow. Then you can go through them with ease. However, I might have this wrong since I am on Leopard and as such, i would just select a bunch, and then hit space to Quick Look them...