If you have an iPhone, I recommend you check out SloPro. It's free to check out but you won't be able to save your movies. For $1.99 you get the full version with more options.
Here the official info list:
- Toggle slow motion while recording!
- Trim and change slow motion afterwards if needed
- No rendering delay--watch slow motion immediately!
- Facebook upload
- YouTube upload
- Upgrade to email, export to camera roll, and export raw 60fps
For non-iPhone 4S 60fps is only on the iPhone 4S. Other devices can still record, edit and share great slow motion videos at 30fps.
The slow-mo sound is fun, especially when it makes your baby sound like a huge ogre beast. :)