There seem to be many possible ways to create man-in-the-middle attacks on public access points, by stealing the access point's local IP address with ARP spoofing. The possible attacks range from forging password request fields, to changing HTTPS connections to HTTP, and even the recently discovered possibilit of injecting malicious headers in the beginning of secure TLS connections.

However, it seems to be claimed that these attacks are not very common. It would be interesting to see for myself. What ways are there to detect if such an attack is being attempted by someone on the network?

I guess getting served a plain HTTP login page would be an obvious clue, and of course you could run Wireshark and keep reading all the interesting ARP traffic... But an automated solution would be a tiny bit more handy. Something that analyzes stuff on the background and alerts if an attack is detected on the network. It would be interesting to see for myself if these attack are actually going on somewhere.