in the Appstore
look at photogenie, phototools also Izoom finally got fixed so it doesn't crash zoom in is new both are pretty similar understand all they are doing is cropping the photo's but they do allow you to see it before you take the photo. but resolution will be reduced these are both 99 cents and those are cheap and work pretty good.
I know these aren't cydia but I have looked as well there just isn't much.