Transferring Images to the iPhone/iPod touch/iPad free, without cable
Now, obviously there are a few ways to do this but my personal favourite is Dropbox. I'd post a link to the website, but I can't because of posting limits (admins: honestly, you should consider dropping them and just add a bunch of moderators to counteract any spamming ). Anyway, if you haven't heard of it, search for it in the App Store. You'll need to make an account, but after that it's easy. You get 2GB of free storage (which can fill up easily, depending on how much you put onto it), but you can pay for more and you get more for referrals (250MB for every friend you get to join, up to 8GB).
It's easy to use (Mac, PC and some Linux distros), all it takes is dragging your file into a folder and it should do it automatically.