Leads & Prospects - Add AGE Field

PRETTY PLEASE add an "age field" to the Leads & Prospects list!!! Whenever I want to email these contacts for specific classes, I have to go into every entry to see the birthdate, then tabulate the age, then make a list of who I should email. For example, we are running workshops for kids ages 3-4 and I would LOVE to be able to go to Leads & Prospects and simple check all the eligible leads to send the email to.