Significantly raise the minimum karma level.

Another technical solution. Not trivial to implement, but also contains significant side benefits.

• Find some subset of sequences and other highly ranked posts that are "super-core" and has large consensus not just in karma, but also in agreement by high-karma members (say top ten).
• Create a multiple choice test and implement it online, which is external technologies exist for already I am sure.

Some karma + passing test gets top posting privileges.

I have to confess I abused my newly acquired posting privileges and probably diluted the site's value with a couple of posts. Thank goodness they were rather short :). I took the hint though and took to participating in the comment discussion and reading sequences until I am ready to contribute at a higher level.