Chrome: If you like looking at images of babies, Facebook is frequently a goldmine of dimples, nappies and general infant cuteness. If that's all a bit much for you, Unbaby.me is a Chrome extension that replaces pictures of babies on Facebook with images of "awesome stuff".
Unbaby.me doesn't use fancy facial recognition techniques, but instead identifies suspect posts based on phrases such as "so adorable" and "precious". You can add your own trigger words (the names of the offspring of new parents being an obvious target). Indeed, you could use this to remove pictures relating to any topic by picking the right words.
The default replacement image is cats taken from Instagram, which to be honest are almost as big a Facebook pest as the babies. However, you can use any RSS feed of images to replace them; simply editing the tags in the default Instagram feed will work well in many cases. Unbaby.me is a free download for Chrome only.