And regarding captchas… Although they can be programmatically solved nowadays, with some effort, spammers have found it much easier to just offer a secondary service somewhere such as a web proxy, and relay captchas they come across to real humans (who believe they have to solve it to continue using the service, unwitting that it’s third party and part of a spamming operation).

The solution to spam is not possible outside of being different. And by that I mean a custom solution that you don’t popularize. For example, I made a small custom forum with a custom captcha. The captcha is extremely basic and it wouldn’t take many lines of code to decipher the three numbers represented in their un-antialiased, 2-color glory. But it’s all custom, with custom file-names etc and no references to any blogging or forum software. Spammers are not a problem at all due to this. It wouldn’t be economical for them to cook up solutions on a site-by site basis.