Here's another ball I want to get rolling... Coaxial and intermeshing rotor helicopters and gyrodynes.
I love the complexity of these toys! The way the rotors often actually intermesh, just like in "real life," is awesome!!
I have a couple examples. Are there any more out there?
U.S. Air Force Gyrodyne by Haji (Sansei)/Sonsco - this one was also released by Cragstan/NGS, but I've never seen the toy itself
Kaman H-43 Huskie by S&E (Suzuki&Edwards) / Rosko
Kaman H-43 Huskie by ATC (Asahi Toy Company) - ATC made a larger version which I'd love to add to my collection someday.