Every hack I made with $40 Wifi+usb openwrt routers before (TL-MR3220):
nas (for my xbox)
home automation (turning off TV at night, I kept forgetting and it was on all night)
internet radio/mp3 player/alarm clock
PVR (I have lovely Hauppauge WinTV PVR USB 2.0 that streams MPEG2 over USB so even my weak router can record SDTV)
Additionally Im going to replace my old Xbox 1 with one of those (even if XBMC doesnt run out of the box, ill be ok with Midnight Commander as my interface
Im gonna experiment with MIPI interfaces. Maybe try to build 720p Camcorder using Cellphone camera module (if hardware encoders are exposed).
Ill definitely try finding cheap cellphone mipi LCD that can be attached to it, preferably with touchscreen.
At this price point this board beats all the 8/32bit AVR/ARM dev boards. I can picture myself putting it everywhere where I need automation.
USB video grabbers are ~$8, Ethernet enabled video door intercom at $40 here we come.