Mac: iPhoto is one of Apple's true love it or hate it apps. If you fall on the side of "hate it", Unbound is a photo manager that does a lot of what iPhoto can do without all the extra junk you probably don't care about.
Ubound doesn't have extensive editing, the ability to create cards or a lot of options for creating albums. However, it is fast and easy to use, which is all that most of us really want in a photo manager. Unbound can organise photos into albums from your keyboard, it uses basic file structure (instead of creating its own separate library like iPhoto), and it syncs up with Dropbox.
That's the crutch and the feature here, Unbound is a great for looking through your photo library and organising everything, but that speed comes at the sacrifice of the editing features.
Still, if that's all you use iPhoto for anyway, Unbound's a better choice. You can check out a free trial on the developer's site.