AASTAT

This is the only TI-83 BASIC program that I know of that
computes mean, median, AND mode. To use this program, first 
run it from the PRGM menu. A ? will appear. Now, you need to
start your list by typing a {. This character is acessable by
hitting 2nd, then the left parenthesis button, right over the 
8. Once you have typed the bracket ( { ) type your numbers 
delimited by commas (for non perl programmers, that means each
number is separated by a comma. Then type an end bracket ( } ).
An example would be {10,54,94,8,1}. Then hit enter. After a 
couple of seconds, three numbers should appear, the Median first, 
then the Mean, and lastly, the Mode.