Well, I personally just read a lot of stuff over this summer and found certain things that interested me. When I found something cool, I read more about it, and tried to think of some stuff to build in that language/framework/toolkit.
You should do the same. Just read about what's out there, and you'll find something that you really think is awesome. Then you'll be motivated to do some coding!
There's tangible benefits to this too - for me, I reached out to a professor to help out with his research in an area that I found particularly interesting (computer graphics). Just ask around!