Python programming ideas

I'm interested in some good Python programs to write to test my skills and learn some things along the way.  So far I've written so very basic programs such as a Klingon to English translator and started on a simple text RPG. 

Does /prog/ have any other ideas of interesting/fun programs to write in Python?

PROFESSIONAL TIP:
Be wary of >>13. It is true that PHP is no worse than Perl, but this does not contradict the wise advice of >>12.  Perl is also a horrible language, and its use will harm not only your /prog/ramming skills for years, but also any system administration ability you may have.