Mapping Routes

[Corsair]

Planning some pretty lengthy upcoming trips and google maps has been an INCREDIBLE help on finding routes that avoid highways/interstates. One thing google doesn't do though is show you the speed limits to various US Routes. Does anyone know where I can go online to find out what the speed limits are on certain streets/us-routes?

I did happen to come across this: http://en.wikipedia.org/wiki/Speed_limi ... ted_States but it's not quite what I need.