Of course right after I posted this I found a good set of links with some apps worth checking out: http://en.irfanview-forum.de/vb/showthread.php?5925-Irfanview-equivolent-for-the-Mac   The one app that I did think looked like a good photo viewer / organizer: Adobe Darkroom.  However, it...

have you ever used iPhoto and irfanview?  They are so totally different that it's not worth the comparison.  You can't just view photos in iPhoto.  You can create a library copy of photos and then the copy is visible inside the application.  That's not "viewing a photo".  You can view photos in...