When giving advice on how to write a good query letter, I've often heard agents and editors recommend that authors compare their ideas to something that's already out there. For instance, I've heard one paranormal romance author describe her books as "Buffy the Vampire Slayer meets James Bond". Well, I just came up with a description of Wayfarer (the sequel to Knife, which I am currently brainstorming) that amused me greatly:
"It's like Thomas Covenant meets Watership Down. With faeries."