These are our current must have non-games for iOS, based on their rating and amount we have used it.
Reeder – Control your RSS feeds with this simple and fast application, I use this one daily.
Omni Outliner – Omni made an excellent job of putting this onto the iPad, a very useful application to have.
Kindle – Read your kindle books on the iPad or iPhone and sync between them. iBooks is a close second, it just lacks content in the UK.
Instapaper- A great way to mark webpage to read later and use for research and info gathering.
BBC iPlayer – If you are in the UK this is a must have. Watch BBC channels anytime and now you can air play to the Apple TV.