When you work on a laptop, the touchpad can get pretty cumbersome while typing on that tiny keyboard. This is a way to automatically deactivate the touchpad while typing.

The touchpad should be enabled again with a 0.5 second delay. The program syndaemon is able to do this.
To make it work, the following steps are necessary:

Look for the Section “InputDevice” that has the Identifier “Synaptics Touchpad” (or similar) and add the “SHMConfig” “on” line. It should then look similar to this:

Section "InputDevice"
    Identifier "Synaptics Touchpad"
    Driver      "synaptics"
    Option      "SendCoreEvents" "true"
    Option      "Device" "/dev/psaux"
    Option      "Protocol" "auto-dev"
    Option      "HorizScrollDelta" "0"
    Option      "SHMConfig" "on"
EndSection

Then restart your Xserver with one of the following methods:

• Log out and in again
• Or at one's own risk with sudo /etc/init.d/gdm restart.

Now the program syndaemon is able to deactivate your touchpad, but the daemon needs to be run to make it work.

To start syndaemon manually, you can use the line:

syndaemon -i 0.5 -d

If you found the option that suites best you can add the mentioned command to the startup programs in the sessions manager (found at System → Preferences → Sessions).