Galangal is a rhizome (root) spice which is very similar to ginger, but with a sharper taste and citrus hints of lemon grass or even soapiness.
It is widely used in South East Asian cooking, especially Thai, where it complements rather than replaces its close relative.
It is fairly easy to get hold of in the UK if you live in an area with Oriental stores, but fresh root ginger is a perfectly acceptable substitute.
Galangal is Indonesian in origin, and can be recognised by its reddish-brown sheen and sharper spears than root ginger.
Allspice
Asafoetida
Coriander
Lemon Grass
Sumac
Za'atar