clone nodeapi call

I like the ability of using what's available as modules in drupal, but sometimes custom little tweaks are needed for specific projects and I like to achieve that using small modules rather than tweaking the code on the module.

I find useful a way of letting other modules modify the $node object before populating the form. Specifically, I want to remove the images from the image fields of a CCK node, as I don't want them to be cloned.

I thought of using a custom module hook, but I believe nodeapi can be perfectly used with a custom op. Here is my small proposal, it's just using hook_nodeapi for it.