These three stocks can help supplement your monthly income.Most dividend-paying companies in the U.S. tend to pay their dividends on a quarterly basis. However, for investors looking for more frequent payouts to help supplement their income, there are some companies that pay out their dividends on a monthly basis.Let's look at three stocks that cut investors a check each month and see whether they currently look like good investments.1. Realty IncomeKnown as "The Monthly Dividend Company," Realty Income (O ...