Larry:

In the work that I am involved with it is necessary to fly as close to true altitude as possible. We typically operate at anywhere from 360' to 18000'. Prior to WAAS enabled GPS we needed to do some math or use a sophisticated "whiz wheel" to determine what indicated altitude to hold to be at a specific true altitude. We've developed a trust for the reliability and accuracy of WAAS enabled GPS altitude and it has made life a little easier.
Even though WAAS/GPS is being developed as a more accurate general navigation system, there are uses and advantages that the original developers of the system never imagined. Makes me wonder: In what other innovative ways this technology will be used?
Regards
Tom Charlton

BTW: Lots of luck getting your instrument ticket. I know you will have quite a sense of accomplishment when you pass your check ride.