I want one of these:
A Garmin 396 Aviation GPS with XM Weather. XM did a great thing and incorporated a weather service for aviation. This allows you to see actual weather right on your screen that is superimposed on your location. Before you could only get something like this with a storm scope radar installed on your aircraft. Not practical for small airplanes, or for large airplanes as you can only see weather directly ahead of you, only for a few miles. With XM Weather you are able to get instantaneous weather over the entire globe. All you need in the airplane is a receiver. Very very cool.
Since I am dreaming, I should want one of these:
The 396's big brother, the Garmin 496. This has terrain alert software that will tell you if you are too low. While the 396 will warn you when you are close to busting airspace, the 496 will shade the restricted airspace a different color so you are very aware about where you are. If flashing alerts and color coded areas aren't enough for you the 496 also has voice alerts telling you to pull up, where traffic is, and warn you when you are about to bust airspace. Very very very cool.
Cool always comes with a price, though. The 396 will set you back $1,700 and the 496 $2,300. Ouch.
As I dream about gadgets, let's pretend I own a 1970's Piper Cherokee Archer II. This is what I would install in to the panel:
The Aspen Avionics EFD 1000Pilot. Essentially the panel of a traditional airplane is made up of circular slots for the round gauges and dials. They are fairly modular, so you can put your instruments wherever you want in your panel. The Aspen allows you to use that and just slip their glass panel in to your existing panel with just a little work to your cover. No need to replace the entire avionics panel like you need to do for other refit jobs.
Combine that with one of these:
Aspen's EFD1000MFD. This guy gives you the multifunction display that gives you terrain mapping, voice alerts, XM Weather, the works.
Again cool is not cheap. The EFD1000Pilot number will set you back $6K, and the MFD will cost $8K. All that is before you pay your local A&P to install them.
Like all things on the airplane, a certified Airframe and Powerplant mechanic must always do the mechanical work to your machine. That is going to run another $4K
Still, putting $20K in to a $60K airplane to get a glass panel is a hell of a lot cheaper than the $100+K it costs to buy a used or new airplane with an integrated glass panel. But those airplanes look like Darth Vader's bathroom:
Cirrus Design's SR22 Turbo flight deck