There's plenty of mapping tools that tell you how to get from point A to point B and how long it will take.

But what about for more exploratory mapping? Say, I live/work at point A and want a job/house no more than an hour away by X mode of transit. Is there any way to plot travel time isosurfaces so I can see a polygon of locations an hour or less from home?

Or say I want to go for a 2 hour bike ride. What are potential destinations leaving from a given starting point?