A fixture in Japanese fan video scene, the MMD Cup is a prominent tournament style contest for 3D animation created using MikuMikuDance - a software tool used for choreographing models of characters like Hatsune Miku. This weekend is the submission period for the 10th MMD Cup's finals, so MMD is hot in the minds of many. Yet, Higuchi Yu stopped development on the tool itself as of version 7.39.
Though the original program, which is being used to create the new anime Straight Title Robot Anime,is still available (you can find tutorials here), the thing to check out is the presumptive replacement MikuMikuMoving. The new tool is backwards compatible with the MMD models, features a more modern interface, English language support, and runs on newer versions of Windows - though not Mac - at least not native. You can find some tutorials here.