Skipping rope helps you learn to be light on your feet, which is good for balance in my opinion. Just don't go slow and steady.. change the pace, try different things, move around while skipping etc. Don't make it a slow, long cardio session.
I do a LOT of balance drills. Especially with my younger fighters. Tomorrow, I'll video us drilling and upload it to YouTube.
For S****, Steelshoulders and anyone else who thinks standing on a log, ball, etc. is going to help balance in anyway: http://www.ncbi.nlm.nih.gov/pubmed/26298214 Also make sure you move onto your heels, and do the opposite of anything s**** suggests. Think about basic physics... widen your base of support, create more contact with the ground, lower your centre of gravity. Practice your balance during the activity you want to get better at balancing at. Developing bigger, stronger legs will naturally lower your centre of gravity, and that strength will allow you to move your body into better positions more easily.