The disposable toilet seat covers from http://www.bluelinehygienics.com are excellent, they have a waxed side to prevent moisture penetrating and they are made from 100% recycled paper.I always take them when I am travelling!
I read recently about taking Disposable toilet seat covers as well because the toilets are below average. I saw that one Kokoda walker paid $15 for 10. I found them at http://www.bluelinehygienics.com and paid $2.95 for 10.