I ran a 2 hour workshop at OSGIS 2014 introducing OpenLayers 3 and Leaflet.

A hands on introduction to using OpenLayer 3 (OL3) and Leaflet to display spatial data on the web. The workshop will introduce the two libraries, the underpinning concepts and strengths of each, and take delegates through creating a series of examples.

The full workshop documentation is available if you'd like to follow along at home.