The new Google Charts API is very very nice.
I still prefer Open Flash Chart for back-office use, but for front-end sites, this might be much better, given that it works everywhere.
One thing to take notice: there is a daily limit of charts that you can ask directly from Google, so if you think you'll use more than those, use a reverse-proxy with cache (like Varnish or Squid) or even have your code call Google API and cache the image locally.
Now, let's see how much longer we'll have to wait until we get a Perl module to generate those URLs. :)
Update: Google Charts API launched the 6th of December, Perl module
Google::Chart the same day. Yeah, Perl is dead.