Carrying the Load

Musicians, how do you carry your instruments if you cycle? Do you strap it onto your back? Strap it to your bike? Use a trailer? Use an Xtracycle? I am looking into carrying an electric guitar (in its hard shell case) and a practice amp (weighs about 30 pounds). I'm thinking this would be a good reason to get the Xtracycle (one of these days...), or rig up a trailer. Any musicians got a cool solution?