Anyone know of a content type images similiar to taxonomy images, but for associating content to a specified content image?

CCK has Imagefield. You can then theme it any way you wish.

Simple method (requires theming/css skills): You can do this with css at your theme level as the HTML will contain class="node-type-xxxx...".

Over-complicated method (only use if you want to manage node types and images/tags associated with them through the Drupal admin UI):

You could have a special vocabulary dedicated to tagging content types. That vocabulary would have as many terms as your site has content types. Then use Taxonomy image to set one image for each term. Then assign a default value (term) for each content type. Then use Field Permissions (or any other module that does the job) to allow everyone to view that field (and thus the associated image) but only admin/you to be able to edit it. This way when normal (non-admin) users create or edit nodes of a content type, they won't be able to change the default tag and image you would have pre-set as default value ;)

Future possible solution (using a contrib module): I would like to bring Content Type Image to your attention. It doesn't have a 7.x version yet (#1477390: D7 Port of the Content Type Image module?), so I'm afraid that it might take long to have a solution if you're using D7. I went on and filed an issue for there that requests this: #1477394: Provide a way to display the image assigned to the content type on node view (node display settings).