Unwritten books

I thought I'd pose a question to the almighty f-list and see what you say.

What types of stories would you dearly love to read, but have never seen written, or not written nearly enough?

For example, werewolves in spaceships or unicorns that aren't helpful, wonderful creatures but evil one-horned ponies of death, or maybe just something as simple as, "I'd love to see a story with a main character that (insert something you think is underdone)".

For me, one book I'd like to see is an urban fantasy novel that is heroine-centric, but the heroine is not the typical leather-clad, beautiful, sassy vampire-huntress, but instead someone who is perhaps not so attractive, damaged, and stops punning long enough to actually fight evil. In fact, I'd love for someone to flip the entire Laurell K. Hamilton/Kim Harrison type novels on their head.

I know I'd like to read a lot more novels in the SF/F genre as a whole that feature main characters that are characters of color and/or disabled and/or transgendered and/or queer and/or otherwise different from the usual. I know that some exist out there, but not nearly enough if you ask me.

So what are the books, characters, plots, and settings that you'd love to read but haven't found yet?