I use my phone. You can use mpd apps or your browser on the phone.
I am still testing the setup, at the moment I mostly listen to web radio via 3G. Works good if you have good network coverage by your network provider.
I am thinking about having a playlist such that if the connection is lost it just continues playing files for a bit and then gets the radio queued again.
After using it for some days now, for me using shairport seems the most feasible solution. Mpd seems some times to have problems with to sudden shut downs, such that it does not start reliably each time any more. (using beta 1.1)
The battery run time with the 4000mAh battery pack is some thing around 4 hours, so a bigger battery pack might be beneficial.
Thanks for your inspiration.
Works great, via iPhone Hotspot, Safari UI.
I am using a 9V Battery pack with on/off switch.
Tomorrow i will try it with my car hifi.