iOS and Windows-only: PhotoSync for Lazy is a desktop and iOS app combination that watches a folder on your Windows PC and syncs any photos inside of it to your iPhone automatically.
Syncing photos to an iOS device is kind of a pain. iTunes goes through an obnoxiously long, CPU-intensive process of converting all your pictures to a friendly size and format that the iPhone will like. Additionally, you have to plug in your iPhone and wait for the entire sync process (including backup) to take place. If you just want to get your freakin' photos on your iPhone, easily, with minimal effort, PhotoSync for Lazy is designed for just that purpose.
It comes in two versions for your iOS device, free and paid ($4). The paid version has no limitations and the free version limits you to 50 photos, but it's a good way to test out the software to see if you like it. You'll also need to download this Windows app (direct download link) so it can watch a sync folder on your Windows PC.
While there's no real configuration involved, PhotoSync for Lazy requires your PC and iOS device are on the same local network so it won't work if you separate the two. Aside from that, the only thing you really need to do is put photos in the watched folder and open PhotoSync for Lazy on your iOS device. From there, PhotoSync for Lazy will start loading the folders onto your device exactly as they're organised on your PC.
PhotoSync for Lazy is available right now for Windows and iOS. It costs $4 if you've got more than 50 photos to synchronise, otherwise you'll do just fine with the free version.