In China, I took the Shanghai Maglev train, which goes 30 km east from Pu Dong Airport into the city, and connects to the number 2 subway line.
It looks like a regular train/airport rail link:
However, since it is basically a tourist attraction, the train actually has display at both ends of each car that tell you how fast it is going. My train reached a maximum speed of 431 km/h (which is about 270 mph). The total trip took 8 minutes, giving it an average speed of about 225 km/h. (On my return trip, after dark, the train only maxed out at 300 km/h).
This is definitely the fastest I've ever traveled on land, given that commerical aircraft takeoff velocity are in the range of 250-300 km/h. (Even the Condorde, which I've never flown on, takes off around 360 km/h.)
And, a round trip ticket costs about 80 yuan, which is around $12-$13 dollars. Amazing