more rails/minecarts variations in Minecraft

more variations of rails and minecarts, each with different abilities, idea suggestions: sticky rails/powered rails can stick into walls sideways and upside down, variable rails which it's speed can be modified by the player, chained minecarts which can connect to other chained minecarts, double minecarts which have 2 floors, a locked minecart which can only be used if you place a certain item in it, the ability to add banner designs to minecarts and much more. This would turn an otherwise underused mechanic into an incredibly useful mechanic that promotes creativity, exploration, and can be used to make fun ideas in buildings, minigames, redstone, and even PVP with the new spears