I just noticed that the PXE bootloader supplied in the syslinux package (in the gpxe folder) is now based on gPXE (link is to a video google have recorded where they show it off) which supports booting the host operating system over a really wide variety of TCP based protocols! gPXE is based on etherboot (or is it renamed now as they merged the projects after forking them).
Previously stage 2 PXE bootloaders (like pxelinux) only loaded things using TFTP, but with the addition of a full TCP/IP stack you can now boot your entire computer over HTTP from a standard webserver located anywhere on the planet.
You can even boot a full copy of Windows using iSCSI without a hardware host bus adapter!
You may wonder why this is relevant to someone that does .NET pretty much all the time like me, but I like to boot servers and workstations off the network for backup/restore purposes, rapidly build test systems in virtual PC and to run new .NET based operating systems that are starting to show up.
Edit: I have noticed a lot of people coming to this article so think it's worth elaborating on the whole PXE bootloader process quickly, basically you do the following:-
Configure your DHCP server (or download one, there's a freeware DHCP server for windows if you don't have a proper server, or you can always apt-get install dhcpd and edit the config file) to serve up your normal subnet plus the addition of a bootfile name called (lets assume you're using PXELinux with gPXE!) gpxelinux.0 (see the syslinux package above and extract this file) and the IP or hostname of your boot server.
Your boot server needs to run a TFTP server, in the root of the TFTP server you put a copy of gpxelinux.0 and a config file for it. For the moment just boot a virtual machine or something and see if it shows the PXE bootloader on startup.
Once you have it loading and erroring about a lack of configuration file, it's time to make a config; for gpxelinux.0 this is just a text file, and there's tons of examples in the syslinux package - but you can just put this in there to get started:-
default local prompt 1 label local MENU label ^Local Boot LOCALBOOT 0 timeout 10 label dsl MENU LABEL Linu^x linux linux24.bin append init=/etc/init lang=us apm=power-off vga=791 ramdisk_size=100000 acpi=off quiet nomce noapic BOOT_IMAGE=knoppix initrd minirt24.gz
And stick a copy of linux24.bin and minirt24.gz from DSL or your favourite small linux system in your TFTP server. I have had great success making those links - so http://yourserver/linux24.bin instead works wonderfully with gPXE.Permalink