Can I share a wifi-connected internet connection over wifi on stock MBP? I have my MBP that is connected to wifi, and I want to share this connection with other devices but via wifi as well.  Can this be done with a stock MBP (i.e. no extra wifi card)?  I enabled this in Sharing, but my chosen wifi network name was not showing up.  MBP is running latest Mavericks (10.9.4).

If this is not possible with stock MBP, would adding an extra wifi connection make it work (e.g. via USB wifi card)?
If you have single WiFi card then you can not use it for receiving and sending WiFi.

If your internet comes from cable (Ethernet) or from a USB -WiFi, then those can be shared using your WiFi card.