[http://www.activestate.com/Products/komodo_ide/ Komodo IDE] from ActiveState is a rich ["IDE"] for Perl, Python, PHP, Ruby, JavaScript, XML, HTML and Tcl. It offers many integrated tools (i.e. code completion, code debugger, regular expressions toolkit, etc).
ActiveState also introduced an open-source, free Komodo-based editor, called [http://www.activestate.com/Products/komodo_edit/ Komodo Edit], which is less functional but available at no cost. [Note: "Komodo Edit" does not seem to actually be open-source - if it is, please provide a link to the source code here. In the actual license shown from the application (both 4.4 and 5.0 alpha), it is copyright Active State. It is also ad-ware, encouraging upgrades to Komodo IDE everywhere. As far as I can tell Active State is planning on an open-source IDE based off of the Open Komodo code called "Komodo Snapdragon", but it's unclear if that will even include Python support.]
The page titled "IntegratedDevelopmentEnvironments" includes several reviews of Komodo. [http://www.unixreview.com/documents/s=10125/ur0704b/ Here], in April 2007, is one of Komodo 4.