I've researched in the past and if I remember, a lot of network cards don't support this feature. What is out there that I may have missed?
I haven't yet encountered a card that it won't work with. I'm pretty sure it's a configuration determined by the software you're running rather than a "feature", so it will work on all network cards. All the configuration really does is pass all traffic the card receives to the CPU rather than only capturing traffic addressed to it. I've used Wireshark in promiscuous mode on an old 10/100 Intel NIC from around 2002, works like a charm.
In Wireshark you can easily check when starting a capture for the promiscuous mode checkbox: