Well there is always a hand crank street organ.. The project that stretched me the most, but worth all the work. You could incorporate lots of scroll work in the case, I did a little on the back of mine, it was built before I really got into scrolling, if I made another, it would have a lot more scrolling on it.
There are also lots of beautiful wooden gear clocks or sculptures. I've been real tempted to do the Humming bird one, but the plans are $100. Too expensive for me right now, but it certainly would be a challenge.
http://www.derekhugger.com/colibri.html
These are for you to think about, personally, with some of the things in my life lately,,,, I want less stress, so mine will be simple things. I want to work on things like some nice Christmas ornamentals to give to family and friends next season. I have a few more difficult things in mind I'd like to try for me and my ego, but at this point in my life, and the stressful environment of things, I want to just relax, keep it simple and give where I can. This may all change,,,,,,, I do like a challenging project and the heck with the family and friends....