I would like to have an enhanced preview window inside LightWave, with thumbnails of previous rendered images and more color, contrast, bloom, ... manipulation tools for the final render. The ability to copy/paste the render (GI, camera, ...) settings from that specific render to the current settings would be great. Sometimes you tune parts too much before you realize that you had better results 5 renders ago.
Also, it would be handy if you could select 2 or more renders to compare with each other. PageUp/PageDown is nice between 2 images in sequence, but not if you have several images in between. A delete button for intermediate renders would already help a lot here.

If such thing already exists, please let me know!