Today, T. wanted Rosetta on the iPad, which I had zero intention of paying for. However, it turns out that when you buy the downloadable/CDROM editions, you get to use RosettaCourse on devices for free, and you can have up to 5 users on those 2 computers, so I set up an account for him and got him going on his iPad.
There's a negative microphone/case interaction on my iPad; I thought I'd fix it by hooking up a headset, but the wired headsets I have all have USB connections. I have a bluetooth headset; maybe I'll try that next.
His largely unsupervised efforts with Babbel and now Rosetta have resulted in a vocabulary of a dozen or so words and/or phrases, and demands for me to spell out loud things like "Salut, maman!" and "Bonjour".
ETA: I dug out the ear buds with microphone, as yet unused, from my iPhone 5 box and set him up. He seems happy.