If you have NBD support enabled in your kernel, you can use this
to read a file over HTTP as a block device. The most obvious use
for me was (is) to mount ISO images without having to download
them entirely. If your linux distribution installer allows early
console access, you should be able to even install the OS from
a CD ISO over HTTP.

Sources are available here.

To use it, compile (you need kernel headers and pthreads
installed), load the kernel module and run nbd-http:

make
modprobe nbd
./nbd-http /dev/nbd0 http://mirror.org/file.iso

(and in another console:)

mount /dev/nbd0 /mnt/cdrom


Due to the nbd driver using the userland process to make block
requests, there is apparently no other way to stop the nbd
userland helper other than ``killlal -9 nbd-http''.

Feedback is welcome at reverse(moc.liamg@cojrah) - Harjoc Bogdan.