Twitter has become something of a phenomenon - if you're not familiar with it, it's a cross between blogging and instant messaging, with a dash of SMS thrown in. You've got 140 characters to say what you're doing right now, and you can build up social connections by "following" and being "followed" by other Twitter users.

One of the cleverest moves on the part of the developers was to open up the API, so that anyone with a bright idea can use the service to mash up for uses that would perhaps never considered otherwise. Everything from news headlines to whether your pot plants need watering, in fact.

Tom and Tom have now taken this one stage further. Our offices are just around the corner from Tower Bridge, which clearly got them thinking - and then coding. So now Twitter users can follow Tower Bridge, which will tweet 5 minutes before it's due to lift, and then again five minutes later to tell you that it's closed again.

Trivial? Certainly. Pointless? Maybe. But a good illustration of how services can be put to uses unimagined by their original developers - and an example of the power of APIs? Definitely.