I have one of these $2000 SD cards in my Diamond DA40. It lets me connect my iPad to my aircraft so I can transfer updated databases, flight plans, and see real time avionics data. It's pretty cool.
Damnnnnn that's cool but ouch. I know you're really buying the whole platform and capability and flight-worthy certification but $2K for what is basically a wifi dongle still makes my head spin.
Aside: Is the DA40 as cool as it seems? >smile<
I've flown some 172s. When the DA40 came out I thought it seemed like a really, really neat airplane. I got some marketing lit and talked to people about it from Diamond at Sun 'n Fun (in 2004, I think). It's nothing I could have even remotely approach buying then (or now, unless I wanted to live in it, I guess) but I just wanted to soak up some of the aura of the thing.
On Cirrus Perspective+ (Garmin G1000NXi) you can just Bluetooth the flight plans over from the iPad. It's really convenient when ATC reroutes me, to just enter it on the iPad and send it over instead of fiddling with knobs/keys.
Database updates are still using SD cards though, but just a normal one as far as I know.