In Chengdu, taxis comprised a significant proportion of the traffic, but nothing like in Bishkek. In Bishkek, most cars will act as taxis. Some people just sit there by their cars and that's the signal that they're taxis. Others have taxi signs that they'll put up when they want to be available.
Since anyone who wants to can be a taxi driver, none of the cars are metered. You have to negotiate a price before you leave (which invariably includes complaining about the cost of fuel), and hope you don't rip yourself off too much. I find that when I first come to a new place, I'm most likely to get ripped off, since I don't know what a reasonable price is. In China, my guidebook is helpful with that, but the one I have that covers Central Asia is from 2003, so all the prices are different now.
One interesting thing about taxis in Bishkek is that the cars themselves come from all over. Some of the cars have the steering wheel on the left, but some have it on the right.
What made me want to devote a whole entry to taxis, though, is how things go after you get in. In Bishkek, most of the streets are unmarked. Houses usually have their street address, so when I'm walking around, I'm okay, but in a taxi you don't have time to examine all the houses. What this means is that sometimes you have to argue with the taxi driver about which street you're on. One night I was taking a taxi with the British jugglers and we had to argue about which street our house was at. Our driver wanted to turn two or three streets too early, and we had to repeatedly call him off until we got to the right one. Luckily, the city is organized in a grid, so I usually knew where I was. Otherwise I would've been lost and the taxi driver would have been foggy about which way to go.
Now I'm in Karakol, a small town by a huge lake and great mountains. I haven't figured out the taxi situation here yet, but I think it might even be worse--they change the street names when the names are too politically incorrect (like after the election a few years ago replacing a dictator-like leader), so many people don't know what any streets are called.