[tszyn]

For my small wiki, refusing all submissions with external links eliminated virtually all spam. Yes, it's drastic, but in my case external links were not essential. I still use ReCaptcha to cut down on spam account signups.

[Blackthorn]

We do that as well, outside of a small whitelist of allowed external links. Turns out it's not enough and we still need recaptcha for a few reasons.

We have a small set of anonymous edits every day, which go through recaptcha to be allowed.