A major goal of mbtaplot is to visualize bus predictions by converting timing information to locations on a map. One thing I've struggled with is how to represent information getting out of date: the longer since we last got a position update the less accurate our estimate is. I think I've got a good solution now, adding a line back from the prediction to the last reported location. The longer the tail, the less sure we are about the position:

The main thing I like about mbtaplot over nextbus or mbtainfo is that because it gives me more information I can second guess the predictions. The goal with this new feature is to intuitively convey more information about the trustworthiness of the information.

(At some point I want to figure out how to get something like this on my phone; the current version uses too much javascript for that.)