Manipulate physical environments: temperature, radio-active waves, etc.
There are companies that professionally crack computer chips for buinsess (chipworks.com).
Smart Cards
Often in credit card form factor
Contains small CPU and non-volatile storage (some contain an RSA accelerator chip)
In stored value systems, the attacker wants to add more money to the card
Alternatively, the attacker wants to extract the secret, to permit counterfeiting of more cards
If an authentication token is locked by a PIN, the attacker wants to discover or replace the PIN
Metro card
MTA Metrocard: central database controlled
Washington D.C farecard: the card itself knows its value. No protection against theft or counterfeiting.
iPhone
All content is encrypted with one of a set of randomly-generated AES keys
These keys are themselves protected: either encrypted with a key derived from a random UID that is stored in a secure, on-chip area, or encrypted with a key derived from the UID and the PIN
Hardware-enforced maximum guess rate of 80 ms/try
Conclusion
Many situations require that some crucial device be in enemy hands
True security in such cases is almost impossible
More than in most situations, this shows the role of economics: the attack has to be cost-effective
This is usually the best approach: make the security good enough