Recently, I attended a data visualization workshop where I found out that there are research fields called Scientific Visualization, Information Visualization and Visual Analytics. Their sole purpose is how to (re-)present data. The scientists in these disciplines do not care much about what they are plotting, just as long as they find suitable, and preferable new, way to plot data. They even have conferences for that! Some professors have developed towards different types of plots and have carefully collected and catalogued as many different examples as they could find, reminiscent of stamp collectors. In the following, there is a link collection to several different sites which specialise in different plotting techniques. If you ever get stuck or bored with representing your data, I recommend some browsing on these sites to get some new inspirations!
If you think, that an important site about plotting is missing, please add them in the comments :)
Tree visualization: www.treevis.net
Biological visualization: biovis.lnu.se
Dynamic graphs: dynamicgraphs.fbeck.com
High-dimensional data: www.sci.utah.edu/~shusenl/highDimSurvey/website/
Three-dimensional data: multivis.net
Performance visualization: hdc.cs.arizona.edu/people/kisaacs/STAR/
Time visualizations: vcg.informatik.uni-rostock.de/~ct/timeviz/timeviz.html
Timeline visualization (yes, there are two of them): www.aviz.fr/~bbach/timelines/
A python library for some more stuff: plot.ly/python/#fundamentals