Create kickstart configuration file from existing configuration

This is one approach I know of. To my knowledge, there is no method to automatically generate a Kickstart file based on system state.

Run rpm -qa --qf '%{NAME}\n' and add to the %packages section in the Kickstart.

Nevertheless, this is not a comprehensive solution for maintaining system standards and builds. This is a more comprehensive answer I wrote on the subject:

Managing an application across multiple servers, or PXE vs cfEngine/Chef/Puppet

Just to add on the Warner's answer. While the rpm query will give you a list of installed packages, it won't help you construct a kickstart file that is close to your system configuration.

Red Hat provides a tool called "system-config-kickstart" which will allow you to use an Anaconda like wizard to create a kickstart file. You could use the tool to configure partitioning information, network, timezone, etc.

Adding the both togther will perhaps help you create a kickstart that is close to your original system.