If you have a Windows Mobile phone or Pocket PC and you ride the MARC from Baltimore to DC (or elsewhere North or in-between), then you might find this pocket sized Excel file handy. It contains an XL Mobile version of the
Fall 2008 MARC Penn Line Schedule.
Note that if you live North of Baltimore, I have hidden those columns, as well as those for Amtrak trains that no longer take MARC tickets for passengers in my area. Later, I'll add the Camden Line as well.
Please note you may need to reality check this. I am not responsible for any errors that lead to you missing a train or anything like that.