You would, of course, continue to receive your base pay. Additionally, if you were receiving a housing allowance at the time of the deployment, you would continue to receive your housing allowance. This applies even if you do not have dependents, and elect to cancel your off-base lease and put your property in storage during the deployment (you would have to pay for any such storage yourself).
If you are entitled to BAS (Basic Allowance for Subsistance), at the time of the deployment, you will continue to receive it (however, you will be required to pay for any meals consumed during the deployment because the military cannot pay you a monthly food allowance and give you free meals during the same period).
If you have dependents and they reside with you, at the time of the deployment, you will begin receiving $250.00 per month in Family Separation Allowance, beginning 30 days after you are separated from them, due to deployment orders. You will also receive Hazardous Duty Pay, in the amount of $225 per month during any calendar month you are physically present in a combat zone. Even if you only spent one minute in a combat zone, you would receive the entire $225 for that month. Additionally, your military pay, earned while in a designated hostile fire area is completely free of Federal Income Tax (you still have to pay Social Security Taxes, and your individual state may require you to pay state taxes, depending on the laws of the state).
You are also entitled to Hardship Duty Pay. For Iraq, this is currently $100 per month.
Finally, if you are entitled to a re-enlistment bonus, and you re-enlist while in the combat zone, the entire re-enlistment bonus amount is tax-free.
So, let's take a married E-5, with six years of service, stationed at San Diego, CA:
Base Pay: $2,205.30
Housing Allowance: $1535
Food Allowance: $267.18
Family Separation Allowance: $250
Hazardous Duty Pay: $225
Hardship Duty Pay: $100
Total: $4,582.48 per month, or $54,989.76 per year, tax-free