Here are two suggestions:
1. Generic thumbnail icons for other item types (documents, audio, video, etc.) that can be used in browse/gallery view and on exhibit pages. Might the code be something like what is mentioned in the "link_href helper function" forum post?
Somewhat tangential to this, we've gotten around this problem for documents by uploading a jpeg of the cover to get a thumbnail and then uploading a pdf.
2. Adding a medium size image view with ImageMagick. I'd like to display a medium size image, say 400-500 px wide on the item record and then click for a larger full-size view. Messing with the database and ImageMagick makes me a little nervous.
Thanks for your consideration.