I do not think they exist at all, unless you hack something together with a notebook's Mini-PCI WiFi/Bluetooth combo card, a PCI to Mini-PCI adapter and u.FL antennas. May I ask what is wrong with using USB?
Both WiFi and BT use 2.4Ghz frequency so they do cause mutual interference. One won't stop the other working by any means, but the more overlapping 2.4Ghz devices you get in a small area (think cordless phones), the greater the interference (noise?) generated.
That said, I've only seen this cause issues with BT headphones/headsets. Just about everything else doesn't care unless you're in a really overcrowded RF/EMF zone.