First off the obvious, Captcha. The bane of all bots but not perfect. While it may slow it down there are entire teams you can hire to do these captchas to continue the spam. You need one for your account creation and when publishing a figg.

Second off, we don't need a limit on how many figgs you can make in a period of time... we need a limit on how many you can make public at a time. If we don't spammers can just create dozen of bots and one day release them all to pubic.

Lastly we need email verification, which may suck if some of us used a fake email, which I recommend they allow us to switch emails in case of an instance of that before they add email verification.