MySociety is a project that has created a tool to help individuals and communities to travel, in terms of cost and time, and offers what some other online trip-planning map services don't:
'Essentially, rather than find travel routes based upon known destinations, you can find out how long it takes to get to certain places using various modes of transit, and choose your destination based upon that information (useful in making decisions about where to work, where to live, or where to enjoy leisure travel).
The colour scale is in hours of total travel time. Warm colours indicate short travel time—red for four hours or less, orange and yellow for four to eight hours—and cool colours longer journeys...Areas with no colour at all...cannot be reached at all by rail and a taxi journey of up to one hour.' (Via Worldchanging)