Uses Cases for Machine Learning?

What are some good use cases for Machine Learning where I can test what I have learnt? Not just cases to test my skills, but ideal cases as well, where an objective cannot be achieved without applying Machine Learning.

Comments

[Wayne Smallman]

Lots, it would seem, but that's the problem:

If the community feels that aiming to solve high-impact real-world problems with machine learning is of limited significance, then what are we trying to achieve?