Hisn Al Muslim App, Invocations from the Quran & Sunnah, is a wonderful app, it contains many Duas (supplications) and Zikr (remembrance) for a muslim to beg every day and in special occasions.
Great features:
A very simple user interface
Unadvertised & Free App
You can use it without connexion
Search of specific Hadit
Create your own favorite list just by marking the Hadit
The supplications are also categorized.