What are the best Apps for toddlers?

I recently purchased a Kindle Fire HD through one of the Amazon sales. I'm pleased with this purchase as I want to teach Joshua about technology. I know there are some toddler friendly apps. I've read what's out there against too much media/technology. I think it's true that too much is unhealthy, but I also think technology can be a good teaching tool. I wanted something for me to sit down with Joshua and let him play along with me. I want to teach him how to use a tablet. Doesn't that sound funny? He's such a little guy! Nonetheless, here are some apps on my phone that he already likes:

• KidsDoodle (this one is his favorite)
• Anything Fisherprice
• Farm Animals (Counting)
• Shapes
• PBS Kids...anything 

So I know some fun/educational stuff is out there.

Any suggestions?