you could try myinterviewtrail.com. You track and upload your interview/travel schedule and in some cases, could find people to split costs with for travel etc.
Our school has an alumni program that lets us stay with alumni in the areas of our interviews. That way you don't have to spend $ on a hotel the night before...they may even be nice enough to pick you up from the airport. At the very least, check and see if they maintain a list of your school's graduates, if any are in the area and if you can contact them to see if they'd be willing to host you.
Some schools offer an interest-free loan for travel/interview related expenses (specifically for this purpose).
Frequent flyer miles are always an option...at least try to consolidate all your travel on one airline so you can rack up the miles. Or some of those credit cards, depending on your financial situation, may be a way to also accumulate miles (assuming you can afford it and pay off your balance, etc. etc. etc.) as some offer various amts of miles for signing up, looking at surveys, trial offers, etc.
Cheaper travel can be found on airlines like Southwest, JetBlue, Ted, AirTran, sometimes Delta. Check out cheaptickets.com or travelzoo.com for a good website offering last minute deals and promotions. I've heard you can get good deals on car rentals from priceline.com. Booking a hotel + flight together (even if you don't use the hotel) can sometimes result in lower fares at the last minute.
That's all I can think of for now....it's not going to be pretty but gearing up for an expensive next three months 🙁