I’ve uploaded a new version of Similar Posts. It allows you to exclude particular authors (if you have a multi-author blog), to specify the text that is shown when no matches are found, and to display the output as, for example, a comma-separated sequence rather than a html list.
Previous versions of Similar Posts used an option page as the sole method of governing its behaviour. This version lets you override those options on a case-by-case basis with a query-style parameter, e.g.,
<!--?php similar_posts('limit=3') ?--> limits the output to three posts. The new scheme allows you to use Similar Posts in several different places in you blog with different behaviour. For example, you might want to display a few similar posts under each post on your home page and also have a longer list in the sidebar of your single pages.