Sequential: fantastic comics viewer for OS X
On top of being fast and crash-free, Sequential is also just plain pretty. It displays EXIF data for photos in nice, Leopard-style bezels, and has all the resizing options you could want for either photos or comics pages. Navigating entire folders is no problem, and there are even next folder / previous folder controls. There's also a slideshow mode, which might not be that useful for reading the latest manga, but comes in handy for batches of photos. Bottom line: if you read comics digitally, Sequential is well worth the download.