Have a look at: http://www.cs.cmu.edu/~10701/projects.html for project ideas. Project A1, A2, B etc listed on the page. You can then apply the toolkit you used in the ML course and solve these and make a portfolio of your ML projects.

Kaggle could be another option.

Else a well defined problem that you may want to solve in a domain: example graphics: See some papers here: http://www.cs.ubc.ca/~van/research/machlearn.html which you could again solve in software.