There are several ways...
#1 have a large enough down payment so you dont need PMI. This depending on your mortgage can save you approx $100+ off your payment.
#2 Pay cash for closing costs.. your closing may only be $4-5k, but it does make a difference.
#3 Pay your homeowners and/or property tax without escrow. Granted escrow does make it easy by diving your bills up monthly, it really depends on your financial situation was to whether you can save your money without escrow to make the payment.
ALSO with room mates, Stash money away when you get it! You can't always count on room mate income, I've had friends get into hard times when that income was gone (IE they moved out lol).
Granted this wont change your payment, but check out Bi-Weekly payments. You pay the exact same mortgage payment amount, but pay half every 2 weeks. This actually cuts a few years off the life of the mortgage since the interest doesn't accrue as quickly.