There is this mod (link) called animal bikes, it allows you to cook rotten flesh in a furnace to make leather, put together 9 leather to get rawhide, and use 3 rawhide, a string, and an iron ingot to craft a saddle. Now, the main part of this mod is, as the name may suggest, lots of ride-able animals(and also mobs). There are many different types with different abilities(spiders can climb like the regular mob :D) and they are all listed on the forum post. I have made a series of challenges/racecourses for each of these 'animal bikes'. The mod is available in multiplayer, and there is also a server on pm which has the mod on it, so you can race against your friends. I plan on making a course of some sort for each mob type.

Additional Notes

Complete:
Reindeer Wreath Course
Snowmobile racetrack