I'm really surprised this nifty plug-in isn't more popular. Adding files to specific pages and posts for sidebar download is incredibly useful and common (at least for us).
I'd love to see the option to set the link target for the downloads. As you know, PDFs can pop in Reader in the same window, thus requiring the user to back track to get back to the page for more.
http://wordpress.org/extend/plugins/list-related-attachments-widget/