I took a photo of the ticket so people would know what it looked like.
This weekend was the first weekend of the MBTA's new $10 weekend fare. For ten dollars you can ride Greater Boston's commuter rail network as much as you like.
This weekend we already had a commuter rail trip planned. This $10 weekend ticket was the price of a single one-way ticket to our destination at normal prices, so it really made sense for us to buy the unlimited-ride ticket.
The pictured ticket is the one you get if you buy one at the staffed ticket window at North, South, or Back Bay stations. You can also buy one on board the train, but that one is only valid for the weekend you buy it, whereas the pre-printed ticket can be bought in advance and validated on the weekend you want to use it. This ticket is also available through the MBTA commuter rail mobile app, but I don't know what the restrictions are for that ticket.
Some conductors on board the trains were being proactive and telling people about the weekend ticket, but not all of them. For some people the $10 weekend ticket was less than the normal one-way fare to their destination so it really would have been a no-brainer.
By the end of the weekend I'd taken five rides on commuter rail, which works out to $2 a ride. Less than a ride on the T's urban rail lines! Quite a good deal.