Evil standard used in the Nintendo DS, but also many other things. It is one of the first mainstream Wi-Fi standards defined by IEEE.
As an attempt to reverse engineer pictochat, I have turned my Raspberry Pi into an epic Wi-Fi sniffer because their Broadcom Wi-Fi chip is just easy to hack and add Monitor Mode (One can even send arbitrary signals over the 2.4GHz ISM band, see: https://github.com/seemoo-lab/nexmon ).
On Linux, monitor mode will mostly use the Radiotap interface, which is maybe not awful, but AWFULLY documented. There is barely any docs regarding this interface due to how obscure this Linux interface is.
Here are a couple interesting resources for capturing and injecting frames: