Here for your delectation is a LibDig WordPress plug-in.
It automatically adds a LibDig box to all your posts
To use it, download and unzip LibDig.zip into your plug-ins directory.
No exciting options or menus yet. I’m sure they’ll follow at some point.
Now updated to only show the LibDig box on posts, not feeds or pages (with thanks to Ryan for a helpful tip on this). Let me know if you’d prefer it that way.