JoJo's Bizarre Adventures has kind of warped my ability to see powers lately. Even lame powers can be incredibly useful if taken to logical extremes. Even the power to manipulate color can be taken to some interesting extremes.

If I wanted to be an asshole, I'd take the power to reset Cause (as in cause and effect) to zero. Basically the ability to reduce actions I choose to zero to prevent any kind of reaction. Even the thought of doing something can be reset.

For a more subdued power, the power to create and manipulate illusions.