When you offer services at a discount to specific clients, how do you reflect this discount on the income statement? Is there a contra-revenue account that offsets the true price of the service?

I don't believe it is reflected in a catergory by itself. The income statement is a synopsis of the general ledger. One the general ledger the individual entry to account payable and receivable would should the discount given, but it would all be totaled on the income statment. The income statement is performance over a period of time such as per quater, but generally over a year. Revenue - expenses = income. The discount would fall under the broad catergory of revenue.