I think the bar which comes on the left side of the Windows 8 picture password screen is ugly, I'd like to make it transparent. I want my logon background to be fullscreen. Any tools/hacks to do this yet?
You cannot, as there wouldn't be any way to switch to a password, for example.
Also Microsoft has restricted most 3rd-party developer access to parts of the UI and experience they deem critical (e.g. you cannot pin your program to the task bar or Start programmatically). UI changes to core Windows functions are pretty much included in that.