Rereading the Spider-Girl trade for my review, a little notion kept tickling the back of my brain, that there was something else here that could be really, really cool. . .and I got a mental flash:
The Peter Parker Mysteries.
Think about it. Yes, Peter isn't an active superhero anymore but he's still a heroic character, more than capable of getting into all sorts of adventures. It'd be Castle meets Heroes, a fun little series of paperbacks in the tradition of the Spenser novels by Robert B. Parker. He may have a prosthetic leg and walk with a cane but Peter Parker is no less a hero than his daughter May, and following him around on cases he's working to solve would be a hell of a lot of fun. Plus, the notion of an older hero dealing with being a father, getting older, and his body no longer capable of the superhuman derring-do of old (whilst still being pretty badass. . .imagine a group of thugs trying to jump Old Pete and him kicking their ass in much the same way as Old Bruce did in the pilot episode of Batman Beyond). I think it'd be sick awesome.
You listening Marvel? Million-dollar idea and I'm giving it to you. If you let me write it. ;p