I'm almost fairly certain this topic has been raised before, although I can't recall if any firm decision was made on it.
I'd like to see more image file types available to save directly out of Terragen, specifically .jpg. I know this is not an ideal file type for production, and I'd never use it for that purpose, but many times, I save out fairly low-res preview renders and having this available would save me a conversion for posting to the internet.
Additionally, other more web-friendly, lossless types would be welcome, as well.