iPXE - open source boot firmware [scripting]
An iPXE script does not have to be a static text file. For example, you could direct iPXE to boot from the URL http://192.168.0.1/boot.php?mac=${net0/mac}&asset=${asset:uristring} which would expand to a URL such as http://192.168.0.1/boot.php?mac=52:54:0...