Hey thanks for these tips, they are really great. I normally change the keys but I looked at some of my old installs, and the keys were missing. This is because they were added in WP 2.6 and although I upgrade diligently, I don't ever update the wp-config.php file, so I'd say if you have any builds that were originally pre-2.6, then you should go in and make sure you've added the keys.

Also the .htaccess trick is simple and genius, probably the easiest thing on this list to implement, so I don't get why people are having trouble with that one.

And finally to quote Kurt Cobain, "Just because you're paranoid don't mean they're not after you".