We are doing a three-week tour of England and Scotland using BritRail passes. The NationalRail.co.uk site is great. for figuring out when the trains run and how long they take.
The downside is that if you have a pass you don't have to make a reservation (and sometimes can't even if you want to). This is only a problem in that most of the the travel sites are designed to record your ticket or reservation info, so it would be really helpful to be able to add the train schedule information manually. Currently there's no way to add it to the Planapple itinerary.

What train systems are people most interested in using? (Or what web sites do you use now to find train information?)