Booking Train Tickets in China has always been pretty decent: there are a bunch of official ticket agents around suburbs and towns, changing ¥5 per ticket as a fee but allowing you to book from the clamness of your own street instead of the crazyness in the station.
Recently it got even better. You can now see availability online, and book tickets at www.12306.cn (if you can read Chinese and have a Chinese credit card, or a friend who can help). Tickets booked in this way can be collected at the ticket agents (for the same ¥5 fee), or at the station (for free). They can also be refunded online, until you collect them (after which you can refund them in the usual way).
And now CTrip, who I have used a lot for domestic flights and hotel bookings offers train bookings too, no doubt in a foreigher friendly manner like their other services. Presumably this means you could even book tickets in advance, so if you’re planning an epic train journey in China this will help.
With these changes, China is definitely moving up on the list of countries with good train booking systems! JUST REMEMBER TO BRING YOUR PASSPORT COPY, as all tickets are stamped with your ID number to prevent scalping (which is good, unless you like getting ripped off by scalpers).