What would you do?
Option 1
You can have $1000 a year for twenty years
Option 2
You can get $1 for the first year, $2 dollars for the second, $4 for the 3rd, doubling the amount very year  for twenty years.

Further Reading:
 Worksheet Exponential Growth (including problems from this page)
 Exponential Decay functions
 Real world models for exponential growth
 images
 Wheat and Cheesboard at wikipedia
 Exponential Growth Interactive Polls (Can you guess the right answer?)