What is the best method to allow a user to attach dynamic, custom content sections to a node? I am looking for a recommended approach for a customization in Drupal I am building.

The desired workflow:
A user will be able to attach N number of custom content sections (CCS) to a node. A user will be able to select the type of CCS (see example below), customize it, and arrange it's order amongst all other CCSs attached to a specific node. 

Example CCS: Enter in the URLs for several Flikr images and the site outputs this as a nice gallery.

I know how to build the individual functionality for each CCS, but I'm wondering if there is any approach you would recommend for the broader functionality.
looks like you need to use comments module for it, you will modify comments by adding more fields to it (for rating etc), then you can attach unlimited such content to your node. if you're in D6 you need to convert your comments to node (using some module) and then add more fields to it by CCK, and if you're using D7 you can attach fields directly (i guess - b/c its entity now)