Python

Scripts

xmlwiko
Allows easy editing of input files for Apache Forrest or Docbook.
dottoxml
Converts DOT graph files to Graphml (an XML DTD that is used by the yEd graph editor) and other formats.
pynoweb
A simple replacement for noweb by Norman Ramsey. This program extracts code from a literate programming document in "noweb" format.
kmailrc
Delete single entries from the "Recent Addresses" list of your local KMail configuration with this plain Tkinter utility.

SCons

I started using this fine build system in 2007 (first post to the User mailing list was 2009-06-19), and got more and more involved in its development over time.

Some of my main contributions are:

I try to fix bugs where I can, improve the documentation toolchain and also maintain the following SCons Tool packages (https://github.com/SCons/scons/wiki/ToolsIndex):

qt4
Support for compiling Qt4 apps, and the tools (uic, lupdate, lrelease).
qt5
Support for compiling Qt5 apps, and the tools (uic, lupdate, lrelease).

Other

Workbench (pysvn)

Some time ago, I used Workbench/PySvn as Subversion client. Although it worked quite well for me, I missed a feature here and there... so I implemented them. All of the following contributions, except for the first two (Update to, customizable toolbar), are still pending to get merged into the trunk.

Support for the "Update to" function.

Customizable toolbar (icon sizes, order of buttons, enable/disable buttons).

Support for the "Switch to" function.

Select the log history entries, based on revision numbers.

A simple repository browser.