For little live code practice problems in python and java there's http://codingbat.com/
There's Google's complete free python class at http://code.google.com/edu/languages/google-python-class/
For a huge library of cs assignments, try the nifty assignments archive at http://nifty.stanford.edu/
http://codingbat.com/ -- free little online coding puzzles, just click and go (python and java)
http://code.google.com/edu/languages/google-python-class/ -- a complete basic python class, complete with pretty neat coding problems ready to go
http://nifty.stanford.edu/ -- tons of fun, medium sized coding projects
Disclaimer -- I had a part in creating all of these.
"God is a comedian playing to an audience too afraid to laugh." - Voltaire