Yeah, I know there are TONS of items out there that let you plug in your iPod on the road. However, anything that is any good will cost AT LEAST $100 (probably much more). Instead, re-purpose an existing product save lots of money, have fun making it and stop global warming :P
A while back the folks at Sirius radio teamed up with JVC and came out with a boom box for their KT-SR2000 Sirius Satellite Radio Tuner. Well I guess the idea didn't work out too well and you can now find these Boom Boxes on a number of places on the web for $20 - $40.
I am not the first one to come up with the idea of using these for iPod use but there is no published COMPLETE "hack" or instructions for doing this (There is ONE website which published one but IMO the instructions were limited and had a couple of critical mistakes). Click .here to see that original post.
I divided this Instructable into different levels: You can stop at Level 1
and get simple amplification of your iPod or go further to fully mod this Boom Box into a completely customized machine.