Help! Creaky Cranks!

What kind of BB is it? The cranks can creak if you have the wrong square taper or if the crank's soft alloy is slightly damaged and isn't fitting properly against whatever pattern/taper the BB is. It's pretty easy to damage an alloy crank especially if it's something like an ISIS drive system.

Its a standard cheapo shimano square taper bb. That's a really good point about the crank though, it might have taken a knock when I was getting the broken bit of the old bb out. Thing is, I think it creaks on both sides, although the chain side (side that snapped) is definitely worse.