Original Purpose: Seasoning and preserving.
Aha! Use: Cleaning tarnished brass and copper. Start with a paste of equal parts salt and flour with a few tablespoons of white vinegar. Apply to your favorite brass candlesticks or copper bowl with a soft cloth and rub. Rinse with water and dry.
Reward: Shiny stuff.
Other Use: Add table salt to the water when boiling eggs to keep the shells from cracking.