for Windows clients

• unattended
  http://unattended.sourceforge.net/
  Automatic OS-Installation including installation of applications. No agent for daily updates.
• wpkg.org
  http://wpkg.org/
  No OS-Installation. Agent for software deployment.
• OCS - Inventory
  http://www.ocsinventory-ng.org/
  Open Computer and Software Inventory Next Generation is an application designed to help a network or system administrator keep track of the computers configuration and software that are installed on the network. (not only Windows clients)
• Automated Network Installations (ANI)
  http://ani.sourceforge.net/
• Real men don't click
  http://isg.ee.ethz.ch/tools/realmen/index.en.html
• diegostart
  http://diegostart.dijuremo.org
  Using PE for OS-Installation.
• symsalabim
  http://symsalabim.sourceforge.net/
  Automatic OS-Installation

for Linux clients

• FAI - Fully Automatic Installation
  http://fai-project.org/
  Automatic Debian-Installation .
• M23 - software distribution
  http://m23.sourceforge.net/
  Automatic Debian-Installation .