It uses the broadcast page api.
Checks it every so often and if the newest broadcast is the same as the last one displayed it does nothing and checks again soon.
If it's different it displays the new broadcast and saves what was just displayed so that it can be used in the previous display check above.

Market bot will be a bit more difficult, at least to give good functionality to which will also hopefully make profit. It would be easy enough to get working but I'd have to sit down and really think hard about how it would decide on what to buy and sell and what price.