If you had 5 months of time to experiment/research something, what would you do?

... in terms of technological concepts, not so much business ideas.

Background: I am CS Master in search of a subject for my thesis. The problem with the propositions I come up with is that I think in business ideas (similar to those http://news.ycombinator.com/item?id=1190974) for useful purposes which (understandably) do not suffice the academic/scientific requirements. However, my department is not really offering any alternatives leaving me in an unfortunate position.

With all the creative and innovative minds present here at HN, I would like to ask: If you could write another thesis, what would you cover today? It would also be helpful if you would share what you wrote about previously. And of course, if your former department publishes their thesis offers publicly, links to that would also be appreciated for inspirational purposes. Thanks.