Here's a great money saving deal which is a no brainer for all who travel on the MRT on weekdays prior to peak hours: Go sign up at http://www.insinc.com/ and participate in their decongestion programme.
You can take the MRT anytime as you wish, but you would receive more credits when taking the MRT during the pre-congestion hours. These credits can then be 'spun' for possible rewards. It's a snake-and-ladder game that generates prizes if you land on some lucky spots.
Thus far, I've received prizes ranging from $1 to $50 in the past few months which I've redeemed from AXS machines to credit into my MRT card.
Have fun decongesting, and learn about the carbon footprint avoidance you're also contributing to as well.