Drexel University has wi-fi throughout campus. Its main wi-fi network, dragonfly3, allows any device to connect using WPA2 (with your student account as your login). But it also has dragonfly and dragonfly2, which are secured with only WEP, but only allow whitelisted MAC addresses to connect (to prevent strangers who have cracked the password from connecting). Each student has a customizeable list of up to only two MAC addresses, editable through a web interface, that they can keep on the whitelist.

When I was living in a dorm on campus, I had two devices (gaming consoles) whose OSs didn’t support WPA2, meaning I had to connect them to dragonfly2. These two devices filled up my whitelist. And occasionally, the dragonfly3 network signal totally dropped out while I was using that network on my computer, while the dragonfly2 network stayed accessible. So then I wanted to connect to dragonfly2 with my computer.

To do that, I had to log in to the web interface, select one of my other devices to unlist, and then add my computer’s MAC address in its place. If I had had SpoofMAC, I could have used it to set my computer’s MAC address to match one of my other device’s. Running SpoofMAC would probably have taken much less time than changing my whitelist through the web interface, and would have obviated the need to re-list the removed device when I wanted to use it again.

The only time I've "needed" to do it is at places that limit their wifi connection times.

For example, the Panera Breads in my area all limit their connection times to 30 minutes during lunchtime. If you spoof your MAC address every 30 minutes, you can keep going.

My old ISP had a MAC white list on its dhcp server. I used MAC spoofing to be able to plug in my own firewall/router.

I had an ISP that would whitelist the MAC address that was allowed to connect to it. When I first signed up, I didn't realize this and they used an old server I had sitting around.

Because their technical support was so awful, it was easier to spoof the MAC of the old server than it was to get through to someone who could actually whitelist my new machine's MAC.

My school had a guest network that would allow people to use it for a few hours, but after that would force them to jump through some sort of registration hoops to get permanent access. Spoofing their MAC addresses seemed to be the easier alternative.