The TravelTime plugin for QGIS comes with a range of options for creating Isochrones (catchment areas based on travel time):
Quick Time Map - runs off an address or map click, with minimal parameter configuration required
Time Map Simple - runs off a layer of points, with minimal parameter configuration required
Time Map Advanced - runs off a layer of points, allowing full configuration of all parameters
Watch below for a short walk-through of how to use these tools.