+1  A: 

Read a file with some data. Sort the data. Write it to some other file.

sbi
That's a pretty good idea. Maybe I'll have a file of simple "records" to show off classes and then sort on whatever criterion.
Derrick Turk
Even "lorem ipsum" will do. Read the words, sort them, unique them, and write them out sorted. Granted, it's not very useful (although as a student I once got paid for writing a program that reads a text and outputs all the words scrambled - you never know), but it has the chance to show some very basic idioms in any language you implement it in.
sbi
+1  A: 

http://99-bottles-of-beer.net/

Brian Postow
Heh... this occurred to me, if only to show off the C++ template metaprogramming version (object code size grows linearly with the number of bottles!).
Derrick Turk
Yes. that site is an excellent way to waste MUCH time, while still pretending to be useful, looking at code!
Brian Postow