1K-SFO -- You may want to consider MBNA Amtrak Guest Rewards MasterCard - no annual fee, 1 Amtrak point per $ spent, and points can be transferred 1:1 into United, Continental and Midwest Express miles, and get 2 HHonors points per 1 Amtrak point (besides other rewards options). MBNA is a great bank to deal with, and it does not charge anything beyond VISA/MC 1% for transactions in foreign curency (for comparison, AmEx charges 2%, and Citibank charges total of 3%).

For more information see http://www.amtrakguestrewards.com/ .