I signed up for an insane promo with Sprint in December where we switched from Verizon and got 13 months of unlimited everything (except 4G tethering, I think that's capped at 10gb per month) for free.

Honestly though, we don't use all that much bandwidth anyway. I'm usually on wifi and for the times that I'm not going to be, my playlists and podcasts download in the background when I am.