WP Security Scan is one of the most highly recommended WordPress plug-ins for keeping your blog secure. This plugin can help you find permission issues with your wordpress install as well as vulnerabilities in your wordpress database and files. One other feature the plug-in has is to show you the details on your wordpress install in regards to PHP and memory utilization. This is very helpful if you are curious to know how much RAM your wordpress install is using, and what your memory limits are as well as what your PHP settings are for your blog.
If you don’t use WP Security Scan, then you should start immediately.