If you have a notebook with one of these large touchpads you might have come across this problem: You type something on the keyboard and suddenly the cursor jumps to a different location messing up your text (because you accidently touched the touchpad with your palm). To avoid this
syndaemon allows you to automatically lock the touchpad when you type something on the keyboard. Desktop environments like XFCE make use of it. The downside of that is, that it can result in a frozen mouse pointer (for some milliseconds or seconds). Therefore I prefer to disable the touchpad manually by using a shortcut whenever I need that feature.
This post shows a one liner which allows you to disable your Synaptics touchpad temporarily. The same command allows you to enable it later again. By binding the command to a shortcut, you can easily toggle between an enabled or disabled touchpad.