Wish you could free your iTunes Library from your computer and take it with you in your pocket? GetUSB.info put together an excellent tutorial on how to run a mobile iTunes Library from a USB stick or hard drive. This method will run the entire iTunes application from the storage device, making it easy to manage iTunes libraries for a mobile user. I believe this is how iTunes should have be developed. Having a library specific for each computer is a frustrating way to enjoy your music if you use multiple computers everyday (ie. work, home, laptop, etc.).
What pushed Greg from GetUSB.info over the edge, was his wife wanting to purchase music from iTunes at work and then sync up iTunes with her computer at home. Typically this is done by purchasing the music and downloading directly to the iPod. But his wife is a CPA and travels from location to location for audits and doesn’t even use the same computer all the time. The solution was to run iTunes from a USB flash drive so she could just manage a single Library.
Read full tutorial: Run iTunes from a USB Drive
Of course this method also works for larger storage hard drives – basically anything that appears as a Mass Storage Device on your PC system. If you are looking for a long term strategy for managing your iTunes music, I strongly recommend doing this process to an external hard drive that is, at least, 120GBs.