The catalogue, which - for the techies among us - runs on Ruby on Rails, gives you all the broadcast dates and details (about every single BBC programme, ever, dating back 75 years) and it's awesomely geeky. It isn't perfect, but keep in mind it's a
Look, here's Joss.
One of its creators, Matt Biddulph, has more details on his weblog, hackdiary.com. There's also a dedicated catalogue blog.