Goblindegook turned me on to this great site, The Insect Company. I'm not a collector but there are some beautiful images there. I've been looking through their images for a couple of hours and thought I'd link to some of the prettier ones here but then I got lazy. So rather than link to the ones I thought were best, I'm going to give you five simple steps to viewing all of the nearly 1500 beautiful images in about 15 tabs in Mozilla (or Mozilla Firebird) in just a couple of minutes. This is worth it, trust me.
If all goes well, you should end up with about 15 pages that each have around 100 beautiful butterfly, beetle and moth images.