What things do you (or could you) claim as tax write-offs?

The obvious ones are mortgage interest, utilities, property taxes, vehicles, safety clothing, etc.

I know a guy who buys shirts with his logo. He gives some away as promotions and uses the rest, himself.

In Canada, with a corporation, we can self-insure for a few thousand dollars of health care costs.

I have a jacket from my last employer with his logo. The justification was that it represented a 5 year safety award, and he got one, too.

What else is there?