CCP14 (powder and small molecule - site is no longer maintained actively)
Jana (Modulated and other difficult structures)
SHELX (structure solution and refinement)
Crystals (structure solution, refinement & visualisation)
The Bari Group software:
SIR 2011(small molecules)
il Milione (macromolecules) and
EXPO (powders)
Platon (multi-purpose crystallographic tool)
Olex2 (structure solution, refinement & visualisation)
Bilbao Crystallographic Server (many useful crystallographic tools)