There are a couple of App's on the App store that have some really good lock screen and home themes and lots of them most of those are free but definitely look for the 5 star rated app's.
I've been browsing along looking for good lockscreens as well, I found a couple good looking ones, but i'm having problems with getting its custom slider to work right. Anyways try out Sublime Lockscreen, iHrt, Typophone 4 and SlantedLock. Those are the ones that I thought looked the best
I think he's talking about wallpapers that you can set for the lockscreen, but those are not as good as themes, as it's only the background, not the slider, etc.