The only bug with it was due to my own stupidity. I wanted a quick way to see how fast a drive was, thus sending one of its large files to /dev/null was fine. Except I went too fast and cp'd the file to /dev/null.
It took a while before noticing I had no more /dev/null on the machine (read: the time needed to fill the rootfs). In a panic, I removed the file.
Seeing the machine collapse due to /dev/null missing was fun.
Each item in the unix filesystem can be one of the following: file, directory, symlink, device node, socket, fifo.
So nothing's stopping you from making it a normal file and capturing all the output programs send to it.
For super funsies you can make it a symlink or socket, but I think most programs won't work if it's a socket.
Nothing also is stopping you from removing it and mknod'ing a /dev/null into another device file, such as the one /dev/full or /dev/zero uses, or /dev/fb0 if you wanna be really silly.
It took a while before noticing I had no more /dev/null on the machine (read: the time needed to fill the rootfs). In a panic, I removed the file.
Seeing the machine collapse due to /dev/null missing was fun.