008_XML_Power_Generators_Notes.xml is a powerful example of how XML mods can do some pretty cool things, with a little extra work on the CMP end of things.

Basically, this XML script lets players buy and equip Power Upgrades on their ships.  If you're planning to use this codebase to add new ships, please note that the CMPs have to have a new Hardpoint added, called "SpConnect01".  Use HardCMP to add the Hardpoint and hide it in the middle of the ship or whatever.

You can very, very easily modify this code to make other things.  For example, you could make power-storage upgrades, armor upgrades, or other things, which could all attach to that point.  Or you could make new Hardpoints with new names, such as SpConnect02, etc., and modify this script to allow players to mix-and-match upgrades... etc., etc., etc.  

So, basically... if you've been wondering how mods like Evolutions allow players to add a lot of new functionality to their ships... this is a good way to do it :-)