Some useful references:
- http://plugins.qgis.org/plugins/FlowMapper/ - appears to be a plugin to help automatically generate a shape file with vectors between origin points based on a CSV
- http://anitagraser.com/2011/08/20/visualizing-global-connections/ (focuses on using Spatial SQL to visualise 'great circles' of airline ODs)
- http://gis.stackexchange.com/questions/27264/how-can-i-map-a-matrix-of-origins-and-destinations-in-qgis
- http://gis.stackexchange.com/questions/59251/flow-mapping-visualization-using-a-road-layer
- http://gis.stackexchange.com/tags/origin-destination/hot
- https://github.com/glennon/FlowpyGIS (A script to create OD data as a Shapefile in Python ... )