Sorry if this has been found already, but I may have discovered a useful (albeit situation and stage-dependent) infinite. I was messing around against a level 9 Wario on Skyworld, and for some reason was having trouble finishing him, so he was in pretty high percents. I ended up with him on the left side of the stage underneath the left floating platform (it was in its lowest position). With his high percentage and the low position of the platform, every utilt would cause him to bounce off the platform and hit the ground. As utilt is ridiculously fast, it was possible to get another one off before the Wario could even get up. I don't know what other stages this works on, or if it only works on Wario, or what characters it works on, or if it is possible to get out of and the level 9 computer was just incapable, but I'm going to continue messing around with this...it looks pretty useful. Once they're in a percentage high enough that they will hit the ceiling, you can utilt them to an instant-death FSmash with no chance of recovery.