Add as attachment for nodes and comments (forum/advanced forum)

I use a combination of CCK, Filefield, ImageField, Filefield Sources, and IMCE to do this. Works great with nodes. Could work for comments if you used the Node Comments module (but I haven't tried that).

There are a couple of caveats. First, recent versions of the Filefield module will only allow you to add files that were uploaded using the Filefield module. You can't select a file you uploaded through IMCE without commenting out one line in the Filefield source. More info here: http://drupal.org/node/441280

The other thing is that if you remove a file from a node and there are no other modules referencing that file, Filefield will remove the file from the server. Adding files to a node body through IMCE via a WYSIWYG editor isn't going to create the kind of reference Filefield checks for, so you could end up losing files that you need if they are added to a Filefield and then removed later. To get around this I implement hook_file_references in my tweaks module and have it always report that it has a reference to every file. That way no files are never automatically deleted from the server. Here's what the function looks like:

function lntw_tweaks_file_references($file) {
  return array('lntw_tweaks' => 1);
}

Closing 6.x-1.x issues as this branch is no more supported.