Vitamin D3 - prescribed by my doctor. I usually buy it from Amazon but during the summer the heat in my mailbox makes the soft capsules stick together so I buy it from Trader Joe's.
If I'm outside a lot during the summer I'll take Med-lyte electrolyte tablets (calcium, potassium, magnesium). Today it's supposed to be 96 degrees with a heat index of 100. Also I take these when I'm doing a very low carb diet and I'm peeing a lot.
Oh, and Centrum Silver (age 50+) for Men multi-vitamin.