My vote is for LogTenPro but I do have the full full program on my Mac. Excellent program.
The rest of my list.
Aeroweather.
PToolbox. Includes metric alt chart and QFE-QNH converter in Hpa and inHg.
Snowtam. Includes temperature altitude corrections.
EUOps. Shame i can't take breaks into consideration.
Fuel Uplift. Uplift and discrepancy calculator, including L-kg.
PDF Expert. Searchable Pdf reader. I have all the books (Pilot Info, SOP, OM etc.) on the iPhone.