Chris- it would help to know the context that you are asking the question.
What are you wanting to accomplish that you feel an app might help?
For me the "Apps/Programs" that are important are"
Quick Office including,
Word- reading files emailed when on the road
Excel- same
PowerPoint
PDF Reader- same
VPN my next phone will have, my 3 G does not.
Bubo Bubo- access to 16 camera system at my headquarters
Camera- use it frequently
All these came with my phone exept Bubo Bubo- some others I use fo work "kinda" are
Tapatalk
Stopwatch