Toiletries and Medical Supplies:
A good body lotion.
Non rince hair conditioner.
Loads of sun protection cream.
The body lotion and hair conditioner to neutrilize the effects of the salt tap water and the sun protection cream speaks for itself. But Dahab is specially a place where you are at risk for sun burn because of the wind. The wind is very comfortable but it will make not aware of the risk of sun burn.
Clothing/Shoes/Weather Gear: Besides your shorts and tee shirts, you should also pack something warmer for the cooler nights as it does cool down, especially if you are planning a trip up to Mt Sinai.