corwin42's libs: AHNavigationDrawer, AHViewPager, AHActionbar, StdActionbarHelper (I think these all should be included in standard B4A installations), without these you can barely create a Standard app
barx's libs: NotificationBuilder
agrahams: Reflection (superceded in most cases by JavaObject), Dialogs (although I dont use it in modern apps, its pretty amazing), Threading, RichString
warwounds: LabelExtras, TouchImageview, OSM, WebviewExtras
Informatix: GestureDetector, NineOldAndroids (i use this everywhere)