EIC- Earned Income Credit (cap is $39k) can be as much as $4,716 (limit 2 qualifying children) depending on your income and filing status... plus an automatic $1000 child tax credit per child as long as the child is your blood or adopted child and live with you more than 6 months of the year ..
http://www.irs.gov/publications/p501/ar02.html#d0e3180
Taken from IRS website publication 501
"Exemptions
Exemptions reduce your taxable income. Generally, you can deduct $3,400 for each exemption you claim in 2007. If you are entitled to two exemptions for 2007, you would deduct $6,800 ($3,400 × 2). But you may lose part of the dollar amount of your exemptions if your adjusted gross income is above a certain amount. See Phaseout of Exemptions, later.
You usually can claim exemptions for yourself, your spouse, and each person you can claim as a dependent.
Types of exemptions. There are two types of exemptions: personal exemptions and exemptions for dependents. While each is worth the same amount ($3,400 for 2007), different rules, discussed later, apply to each type."
The six months rule doesnt apply to newborns either.
"Death or birth of child. A child who was born or died during the year is treated as having lived with you all year if your home was the child's home the entire time he or she was alive during the year. The same is true if the child lived with you all year except for any required hospital stay following birth"
All the requirements for claiming an exemption for a dependent are summarized in Table 5.
Table 5. Overview of the Rules for Claiming an Exemption for a Dependent
Caution. This table is only an overview of the rules. For details, see the rest of this publication.
You cannot claim any dependents if you, or your spouse if filing jointly, could be claimed as a dependent by another taxpayer.
You cannot claim a married person who files a joint return as a dependent unless that joint return is only a claim for refund and there would be no tax liability for either spouse on separate returns.
You cannot claim a person as a dependent unless that person is a U.S. citizen, U.S. resident alien, U.S. national, or a resident of Canada or Mexico, for some part of the year. 1
You cannot claim a person as a dependent unless that person is your qualifying child or qualifying relative.
Tests To Be a Qualifying Child Tests To Be a Qualifying Relative
The child must be your son, daughter, stepchild, foster child, brother, sister, half brother, half sister, stepbrother, stepsister, or a descendant of any of them.
The child must be (a) under age 19 at the end of the year, (b) under age 24 at the end of the year and a full-time student, or (c) any age if permanently and totally disabled.
The child must have lived with you for more than half of the year. 2
The child must not have provided more than half of his or her own support for the year.
If the child meets the rules to be a qualifying child of more than one person, you must be the person entitled to claim the child as a qualifying child.
The person cannot be your qualifying child or the qualifying child of any other taxpayer.
The person either (a) must be related to you in one of the ways listed under Relatives who do not have to live with you, or (b) must live with you all year as a member of your household 2 (and your relationship must not violate local law).
The person's gross income for the year must be less than $3,400. 3
You must provide more than half of the person's total support for the year. 4