Can I create a boot disk for 10.6 or 10.7 on a PC (to be used on a Mac?) I have a Macbook Pro that had a hard drive failure, I've replaced the hard drive but I don't have a boot disk of any kind.  I could just order a Snow Leopard DVD, but I have to wait a few days for this.  So I'm wondering if it would be possible to download either Snow Leopard or Lion to a DVD from a PC that I have access to, that I could then use as a boot disk on the Mac.  Is this possible?
Is it humanly possible, if you received an ISO from some source, that you could create a burnable disc from a PC? Yes, no reason why not.
That being said, if you have upgraded the firmware on a recent-enough MacBook Pro, and have a fast enough connection to pull down a OS install disc, you could use internet recovery:

Apple's Knowledge Base Article for Internet Recovery-Capable Macs

I believe this won't work if you hadn't run this updater on your Mac after already upgrading to Lion, but it would pull down a recovery partition of less than a GB first, from which you could at least browse the web with the 'get help online' Safari Kiosk mode, or go on to do a full reinstall.

Beyond the 10.6 disc, there is also a USB drive for Lion that can be purchased as well, of course. Good luck