Contesting Software
Writelog
N1MM logger
Ham Radio de Luxe
MixW (no freeware)
Swisslog
SP7DQR SWL software
SP7DQR DX contest
 
Contest Calendar
WA7BNM
SM3CER
PG7V
Logbook
For logging contacts, regardless the mode, one can use socalled logbook software. With the more extended logbooks one can also keep tracks of his/her DXCC status, awards, etc.
In most cases the "stand-alone" programs also have the capability to use them to make (digital) contacts, but also to control your radio, your rotor, etc. It is also possible to obtain assistance from the specialised forums, but ofcourse only after you read the manual
DXKeeper
Logger32
XMLog
Ham Radio de Luxe
MixW
Online Logbooks (In these cases registration is neccesary)
Clublog
LotW (Logbook of the World)
eQSL
QRZCQ
 
Look at eHam for info about lots of other logbook software
Special logbook for SWL's
Digital contacts can also be made using:
MMTTY
MMVARI
MMSSTV
Digipan
   
For printing labels, QSL-cards, etc. one could also use:
BV7
HAM Secretary