Pat Hawks

dirtysuds

Once activated, Gallery posts will have an excerpt that is a row of thumbnail images from that post, rather than some (often not descriptive) text. 
This excerpt should appear in your archive pages, and perhaps elsewhere, depending on your theme.
Note: The post must actually have the post type ‘Gallery’. It cannot just be a post with a gallery in it.

Gallery Excerpt

Replace the excerpt for posts with the post type 'Gallery' to a row of images from the post.

Patryk

Add custom content to post and/or page (top/bottom). You may use text, HTML, Shortcodes and JavaScript. Simple, but work…

PRyC WP: Add custom content to post and page (top/bottom)

Works exactly as described. Does exactly what I need it to do. Adds custom content to all posts at the bottom and/or top, which is perfect to keep old posts updated with current affiliate links on my blog! Excellent! You can also add content to the top/bottom of pages. Does not add content to the excerpt (rightly so).

Only downside is that there is no visual editor. Not a show stopper for me though. :)

Does exactly what I need it to do

Add custom content to post and/or page (top/bottom). You may use text, HTML, Shortcodes and JavaScript. Simple, but work...

Gallery Excerpt vs PRyC WP: Add custom content to post and page (top/bottom)