I developed several software add-ons for Plone some years ago now, that have not been updated for more recent Plone versions. First, there were several general-purpose add-ons (called Products, back in the day):

BookAnnotation , for building web pages using javascript tooltips to show definitions/annotations.
VoyageOfTheBeagleByDarwin a folderish Archetypes-based Plone/Zope product for showing the full text of the book along with web links provided by the user for selected terms and phrases
StudyGuide , featuring a checklist for items in a study outline. Students would rate each outline item for knowledge level on a scale from 1 to 5, and make there own note about the item. A graphical representation displayed after saving with knowledge level shown as horizontal bars, with a check mark for those items scored at knowledge level 5.

Second, there were Plone add-ons focused on generating graphics:

GeologicTimeScale , a time scale drawing program written in Python for the Plone/Zope website system that uses the ReportLab graphics toolkit and custom programming for SVG generation. This was the application used to develop the graphics-generating functionality.
TeachingSchedule , a calendar layout program for presenting a visual chart of overlapping teacher schedules.
VacationPlanner , similar to TeachingSchedule, but for presenting employee scheduled vacations.
EarthMoonSun , which used the ReportLab toolkit to generate graphical views of the Earth-Moon-Sun system, orbital positions of these three bodies, and moon phases.
SmileyFace , which was a simple add-on in most basic form.

Other older software projects include:

TagCloudImage , did a little filtering on text to remove stop words and common words first, then the Python Imaging Library (PIL) for graphics generation.
FieldCount , a Python program written for Linux handheld devices such as the Sharp Zaurus. FieldCount used the Qt GUI framework, via pyQt.
StratDraw , a Java program for drawing geological measured section illustrations. It was a significant effort, but the code is for a fairly early incarnation of the Java Swing framework, and if updated, would be rewritten in Python or Javascript, perhaps.

Regarding these unkept, unfinished projects:

Hoping to fix that... December 2011...

Current Programming

Javascript , for web apps, using the SproutCore framework
Python , for general purpose, and backend work, mostly using the Pyramid framework, and a variant called Kotti , and also Plone
Node , for backend work, mainly in helping with development, mostly testing, of Thoth , a SproutCore-related framework

Languages Used

PL/1, Fortran , had classes in the late 1970's
C , for general programming, and for DOS GUI
C++ , for computer mapping and X/Motif GUI
Java , for a subtantial desktop app and Java Server Pages development
Visual Basic , for one business app
Python , for general purpose, for Plone, Pyramid, etc.
Javascript , mainly with SproutCore
Node , mainly with Thoth