[alagappanr]

How about an SMS verification code sent to the user's mobile phone?

[jrockway]

Mobile phones are $30 at your nearest bodega.

[joshschreuder]

Meaning that multiple entries are very cost-prohibitive. If you want to enter 100 times with Facebook, you can buy 100 Facebook accounts for much cheaper than the $30 * 100 mobile phone cost.

[jrockway]

In that case, you can just get a VOIP number for 8 cents or whatever.

[shawndrost]

It might be possible to prevent this. Craigslist somehow detects when you use a Twilio number.