Basic data structures:

linked list, binary tree, hash table, stack, queue

Design Patterns: Millions of these, but these of some of the absolute core

Creational
----------

http://en.wikipedia.org/wiki/Creational_pattern

abstract factory
factory
lazy initialisation (lazy loading)
singleton

Behavioral
----------

http://en.wikipedia.org/wiki/Behavioral_pattern

command
iterator
observer
strategy

Structural
----------

http://en.wikipedia.org/wiki/Structural_pattern

adapter
composite
decorator/wrapper
facade
proxy

Presentation
------------
Model View Controller (pedants argue this is an architectural pattern not design)

OO Principles
-------------

Decoupling
Encapsulation
Favour interfaces rather than implimentation inheritance