I believe this was asked before and we arrived at the consensus that it is extremely hard to answer without knowing anything about your interest and skills, but that it is suitable for the forum section. There is already a entry like this in the forum, so I see no need to keep this one here.

I don't share the consensus referred to by Michael. I think there are a lot of people here who could easily throw out ideas that would make problems for master's students to tackle. Your question might be a little annoying to some as it is asked so broadly, but I think people should just get over it and kick out a few answers - it's phrased exactly as if you had asked it as a new student making small talk with other students in a coffee line somewhere. You might expect some coaching on specifics. Michael referred to a similar post, but did not link to it. At the very least, you should check for similar posts, before asking a very similar question (I can't defend you on that account).