If you’re hosting your own .safariextz file using Apache, make sure to add:
AddType application/x-safari-extension safariextz
to .htaccess in the hosting directory, or instead of downloading it as a binary file, users may get a page of gibberish when they click on a link to it.
Just a note: I’ve made a point of adding tags to just about every post. That means that you can find similar posts by clicking on a given post and clicking on a tag.
I don’t guarantee perfect tagging, but I’ve tried to add the same tags to similar, common items. See, for example, the items tagged with “Google Reader”.