The TSA's ridiculous limits on liquids and gels have had at least one beneficial side effect: you're forced not to overpack heavy liquid-based toiletries that you don't really need. You can buy just about anything anywhere; it's not like people in China don't brush their teeth. Plus, it turns out that there's good alternatives out there for things like shaving cream. On short trips, it makes sense to pack your toiletries in advance; if you're going to be spending months between airline flights, bring the bare minimum and plan on shopping locally.
If your local Wal-mart or Target can't cover your travel-size needs for liquids, just try searching on Amazon.
Little details can really matter. Though it might sound ridiculous, buy a toothbrush case that is flat-sided, like this one, rather than the more common round holders. The round ones will roll off the counter and ruin your day.
It might sound ridiculous, but bring pocket tissue packets. Always have a pack on your person somewhere. Even if you don't need to blow your nose that often, you will find a bathroom that lacks toilet paper. Or you will need to wipe dirt off of your hands, or clean up after a meal.
A big can of shaving cream is going to take up space in your bag. So will an electric shaver. Instead, just get yourself a good razor and some shaving oil. A 12-milliliter, half-ounce bottle of Somersets shaving oil will cover you for three months. This stuff is so good that I specifically order it from their Web store in the UK for my trips.
On a related note, it's worth mentioning that one thing I did have trouble finding in much of Southeast Asia was after-shave lotion. It's not that you can't buy it; it's that every single brand -- and these are Western brands, like Neutrogena -- contained some kind of skin-whitening ingredient. What this says about local cultures is a topic for another day; the fact is that whitening was the last thing I needed.
You may also want to bring insect repellent with you from home. I was unable to find DEET-based repellents outside of the US; maybe other parts of the world are nervous about skin products that can melt through plastic bags and strip paint off of the walls. (I wonder why...). Still, DEET repellents often seem to be the only thing that reliably work against mosquitoes. While REI's Jungle Juice is the strongest stuff out there, 3M Ultrathon insect repellent is easier and cleaner to work with, making it my personal choice. Both are small enough to fit in your 1-quart plastic carry-on bag.