I need an open source disk imaging application (something like Ghost or Acronis). Which one would you suggest?
My personal choice is PING (Partimage Is Not Ghost) as I've used it considerably at work and at home, with much success. We've got base images for our most common machine models. 1.5 - 2 Hour builds down to 25-30mins depending on the machine.
So far I've only tried backing up to another partition or a USB drive, though it does support backing up to a network drive.
I've heard good things about FOG as a Ghost alternative. No personal experience to back that up, however, as I used a custom PXE solution before FOG was available.
It is definitively not "open source", but maybe still good enough and has an API: Imagex / WIM files from the Windows Vista AIK toolkit. With that free download you get Windows PE and the imagex command line tool. It will make a file based image of your ntfs drive into a WIM-file which is single instance, compressed and stores everything you need (ACLs, owner, streams) and only skips pagefile if you want.
It's very easy to use, e.g. over a mounted network share!