#2 Jan 19, 2006 02:50
Instead of having one trackback url for each post that's listed on the site how about dynamically generating trackback urls as requested by users. Don't list the trackback url on the post page, instead give a form for requesting a private trackback url. This would give us a place to use a captcha to verify a real user. Each user would get a unique and randomized trackback URL that would be valid for only one trackback. The temporary URLs and which article they are associated with could be stored in a new database table and a function could snag incoming trackbacks and post them to the appropriate article.
Not a unique thought, its been done : see my blog... http://www.village-idiot.org/archives/2006/01/17/the-duke-of-cleveland/
user-generated trackback with a unique and expiring key, and i should tell you that I get NO trackback spam. I do see ocassional spam comments that get nuked immediately (i get the email, by choice) But absolutely NO tb spam.
This wouldnt be a difficult thing to code for b2evolution, and its even simpler than you suggested.