Another useful gauge the ScanGauge II displays, that our cars don't have, is a voltage gauge. At a glance you can see what your battery voltage is (i.e., VLT=14.2, for example).
Here's a list of the main gauges:
Fuel Economy
Fuel Rate
Battery Voltage
Coolant Temperature
Intake Air Temperature
Engine Speed (RPM)
Vehicle speed (MPH)
Manifold Pressure (not available for gas Beetles, but there seems to be a code that works for TDIs)
Engine Load
Throttle Position
Ignition Timing
Open/Closed Loop
Maximum Speed
Average Speed
Maximum Coolant Temperature
Maximum RPM
Driving Time
Driving Distance
Fuel Used
Trip Fuel Economy
Distance to Empty
Time to Empty
Fuel to Empty
Last but not least, The ScanGaugeII allows you to troubleshoot your own car, read error codes, and the conditions present when the error occurred. Not a replacement for the VAG-COM by any means but a nice feature in addition to all of the rest of the things it does.
At the risk of being continually redundant, here is a link to my previous ScanGauge II link:
ScanGauge II