surf housing... go for a swim and shoot some surf. its a good time and a good learning expeirience.
in fact... i am selling my first home made one that i made last year. basic fiberglass housing. no leaks. not pretty but functional. $250, built like a tank.
shot all the surf stuff on my site with it when i was interning at Surfer Magazine. www.joshturnerphoto.com
other than that a hard drive is a really good idea. a super wide angle would be nice for those landscapes you will be shooting. the sigma 10-20mm is a pretty solid ultra wide, and less costly, and frankly is better than the canon 10-22mm