I recently picked up the much maligned Kid Kool for the NES at the Flea Market. While the game play and design has significant problems that hurt the overall game experience badly, the ability to jump super high and far as well as to skip across the water with keep bringing me back. Kid just soars when he jumps if he builds up enough speed, which plays horribly with the level design and upward screen scrolling, but, regardless, is a thing of beauty from a game that cost me $3.
What other retro games out there have unique/noteworthy jump mechanics?