I think the list of apps on iPhone only is actually pretty extensive. A lot of the apps will show up much later, or will eventually end up with an analogous app but not necessarily the original.

Some examples: -MindBody Yoga. A directory app for yoga classes -Angry Birds. Took 6 months or longer to end up on Android -Qrank. I don't think they have an Android app -Pictureka. At least when I was playing it, they didn't have a version on Android. -AirBnB. I think they only have an iPhone app etc... I can go on for a while... :)