Some things I would like to do, in no particular order:

* Backpack Europe and ride Eurorail

* Build an amateur radio transceiver

* Read the Iliad and Odyssey

* Learn ballroom dancing

* Learn how to make paper

* Learn to cook (!)

* Camp in every national park

* Buy a used motorcycle and learn how to fix it up

* Learn to play the banjo

* Build a 12" Dobsonian telescope and attend star-parties

* ...

May I recommend the Fagles Iliad and the Fitzgerald Odyssey?

Learn to cook, everybodys advices me about cooking ;)

re: eurorail.

It's scenic but something like ryanair.com is cheaper and obviously faster!

You’re lucky.

During my academic hiatus, I found that fostering a personal liberal arts education was incredibly helpful. Reading literature, playing sport, and learning some elementary computer science have been incredibly (and unexpectedly) helpful in my academic areas (mathematics and economics). Therefore, I’d suspect your interest in language and sport might also be incredibly worthwhile (and conceivably) beneficial activities to pursue during your hiatus.

I'm about to take a semester off to work on a start up company in China. I would recommend doing something with your time that will combine multiple interests. I think doing something abroad would give you 'international' experience, allow you to travel and give you opportunity to learn a new language. As for martial arts, I'm biased, have been studying Ninjitsu (Budo Bujinkan Taijitsu) for the past 5 years. Ninjas rule.

Don't dismiss the oft-maligned joys of idleness. You might not get much time to do it later!

Some martial arts ideas: Learn jiu jitsu (gi or nogi) and compete as a beginner. You'll get addicted to learning it and you'll want to fit in 1-2 hrs of training per day

My friend is learning jujitsu and totally loves it. I haven't yet got around actually doing it myself but should be fun.

Besides whatever else you choose to do: get in the best shape of your life.

Not sure how old you are but this is great advice. Taking time to work out (run, lift weights, box, do whatever you enjoy) will pay massive dividends in the future.

Also make sure you're in great emotional/mental state. Sleep a lot, enjoy yourself, and get pumped to do whatever you want for a year.

You should travel, if you can afford it.

me and my brother have decided to learn wing chun. seems very interesting.