Check out http://www.gunnertraining.com/free_trial/1175524 It's a website of Step 1 flashcards and it does spaced training, meaning that if you already know a card really well, it won't show you those cards, and will focus on things you're having difficulty with. I've been using it for almost a month and really like it. The link I provided will give you a free 1 month trial. Hope it helps!