Going to take a look at them soon! (Work has vid's blocked!)
I'm also looking for add-on/ideas to add to an i3, too.
I've ordered parts for my bed leveler and will print required parts today!

So far I have:
LEDs on the bed
Auto Bed-Leveling
Bowden (never tried this)
Dual Extruder (maybe, not a fan)
LCD (built into the frame)
Network the printer (R-Pi or BBBlack)

Any more?