How can I prevent spam on sites which I control?
Specifically trying to combat things like this! http://www.autopliggdotcom (didnt want to give them a link!)
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The problem with coming up with a solution is that if it is posted on the internet, autopligg will just find a way around it. To fight the spam I have had to hack Pligg and come up with custom methods to keeping spam at bay and even at that, spammers still find a way around my defenses. My suggestion to you is to keep up-to-date on the latest techniques in spam prevention and create a custom anti-spam system unique to your installation of Pligg. Then change it up every so often to keep the spammers guessing. Some of the techniques that I use are capcha, nonces, and akismet.
The most effective way to stop spam sign ups with Pligg is to disable signups. Because, to be fair, I think, Pligg is just a flawed platform :/
But if you do have some financial returns from your pligg, then: