Hugh Hewitt's website has a list of these races.
Bush can advertise with GOP. You saw those ads, didn't you? "President Bush and leaders on the congres...." They share ads 50/50. It is a backdoor that Karl Rove has figured out. Moreover, GOP can advertise on behalf of Bush also independent of $75 million matching funds.
The President gets federal matching funds now and is fully funded, so if you want to send someone money, send it to these guys.