My favorite apps are:
Graphic:
Maxxon CAD
DynaCadd (3d CAD)
CAD2CNC (converts 3d-CAD- to CNC-files)
UConv
MetaView
PicShow
MiniPicShow
ArtEffect
ICS
ScanQuix
FxScan
FxPaint
Maxxon Cinema 4d
MoonZoom (aka Reflections)
ElasticDreams
FantasticDreams
PictureManager
TurboPrint
...
Office:
FinalWriter
AmigaWriter
PageStream
APDF
Superbase Pro
TurboCalc
GPFax
BurnIt
ViCaDo
...
Music:
ProStationAudio
ADrum
Sonix
AudioMaster
TB303
Octamed
Ncoder
SOXX
...
Science/Engineering:
MathAmation
FuncPlot
LogicWorks
Newio
DigitalWorkbench
...
... and of course loads of system tools like SnoopDos, CrossDos and the like.
