My favorite MTA subway/bus hack is getting a round trip for a single fare. It’s not always possible but when it works it works.
I take a bus from Long Island City to midtown and, if I take care of whatever I have to do there within 2 hours, go to a subway and get a free bus-to-subway transfer back to Long Island City.
I don’t think this hack could ever cost the MTA too much. There are so many people who, for reasons I’ve never understood, simply will not ride the bus. It doesn’t matter if it’s faster, if it takes them to the front door of their destination, or if using it in the way I just described would cut the cost of the trip in half. A lot of people out there simply refuse to ride the bus.
This hack also can only be done with a cash card, which regular commuter typically eschew.
Last week I found a 7-day MetroCard with 3 days left on it. In the past I’ve found 30 day cards with most of the month’s fare still on it. I don’t ride the subways so much any more but when i find something like that I milk it for what I can. Last week i rode the freebies pretty far, using the found MetroCard to get to the American Museum of Natural History where I used the free idNYC card to get a free membership there.