Having a featured image isn’t a requirement for many layouts, but there are times when you’d like a specific page to display a featured image no matter what. It becomes problematic if there are posts that don’t have a featured image. This is where the Default Featured Image plugin By Jan Willem Oostendorp comes in handy.
Once installed and activated, go to Settings > Media and set your default featured image. Save your settings and your done!
For more detailed instructions, check out How to Set a Default Fallback Image for WordPress Post Thumbnails.
Related Ideas
After implementing this on Couch Baby, I started thinking about what if I wanted to automate this per category, meaning set a different default image per category. I haven’t done it yet, but I’d probably start here.