iPhone/iPad: Finding apps on the iTunes App Store has become something like an endurance trial these days, so it's no surprise that we'd start seeing apps devoted to finding other apps. Discovr Apps costs $1.19, and uses apps you've already installed on your iPhone or iPad to map out similar apps that are available on the market. Basically, it's like the Visual Thesaurus, only for apps.Tapping on an app once will expand the tree to show more similar apps, while double-tapping on an app will slide you to a screen showing all the iTunes info for it—except it's actually a nicer interface than iTunes itself. The app is also surprisingly quick as it maps out apps, both the first time and as you expand it.
If mapping things out can help find just a few good apps, then the $1.19 might be worth it just for the sake of convenience.