Throw away your USB sticks! Forget about Linux install CDs! Be ever-ready for any data transfer or OS installation need! Install DriveDroid. :)
The premise behind DriveDroid is simple. It turns your phone into a USB drive. The application can either use an ISO file (e.g. to make a Linux boot CD - the application includes links to download these from the app itself) or you can create 'empty images' which effectively turn your device into a fully read-writable USB stick.
I tested the application with both those different scenarios - I booted Ubuntu on my machine using only my phone and a microUSB cable and I plugged my phone into my Mac whereby it appeared as an empty USB drive (100MB, because that's the capacity I chose) and I was able to copy files to it, unplug, then plug back in and pull the files off. Awesome!
I tested using my HTC Butterfly - all good - let us know how you get on!