wvmarle:
Jumpers are not a good idea for anything but prototyping - that's also where breadboards come in.So when you know it works, get out that soldering iron to make proper, lasting connections, indeed soldering multiple wires to the pins, and then put it all in a nice little case.
trust me, i have a few things that i would like to do that to but i'm not gonna use an arduino for each, when i get better (if, i get better) at this stuff i'll look into minis.. battery voltages will be a struggle for me as i do no know how much juice is required for each to last a long time to use one of my projects.