A couple of days ago Beijing added several more subway stops and subway lines, making it the largest subway network in the world (surpassing Shanghai).
This website offers a good subway map with the ability to estimate the time to travel between stations: http://www.explorebj.com/subway/
They also have a good app although it is under approval now. Google maps are also very good as you can zoom-in and see the actual exit number closest to where you wish to go but Google has not updated its map yet.
Notable new stations include:
- Panjiayuan (line10): which gives you access to the market of the same name (better visited in the morning on weekends)
- Beijing West station (line 9): for the train to Xi'An (this station is not new as such but is now connected to the rest of the netword)
- Nanluoguxiang: Gives you access to the pedestrian street of the same name and surrounding hutongs. It is also walking distance to the Drum Tower.
- Beihai north: not sure where the exits are exactly but this is supposed to be next to Houhai.
Fares are still 2RMB and the subway is always there where taxis are nowhere to be found.