I was inspired by a piece of armor in the video game Halo Reach to attach a GPS module to my arm. The only GPS I have is on my Droid X2.
It's practical for texting, GPS navigation, and talking with speaker phone.
I timed it: it takes about 1 minute for your arm to get tired when holding it in front of you.
Takes about an hour to print.
Use with armband of your choosing. I use a work-out armband, it's loose though.
The rubber case for the Droid must be used, otherwise you risk scratching the phone and it will slide out of the adapter.