The American Express Platinum Business Premium Cash Rebate Card is again offering a
$250 statement credit (update: removed) after your first purchase, with no annual fee. If you got in on this last time like I did, you may not be able to get it again unless you have a 2nd business – “You may be permitted to have more than one American Express? Business Card account; however, you are eligible to receive only one promotional $250 statement credit per unique business.”
Added: I just saw this if you click on “Special Offer” in the upper-left – “Note: Only business owners who received this offer via Inc. Magazine qualify to apply for a Card through this website.” I don’t remember seeing that last time, so watch out.