I've released the next iteration of the Feed Statistics plugin for WordPress. This version (1.0.4) adds statistics on which Web-based feed readers your subscribers are using, which you can view on the Options > Feed Statistics page.

Download the zip file of the newest version here, and overwrite feed-statistics.php in your blog's wp-content/plugins/ directory if you downloaded an earlier version. If you're downloading it for the first time, just copy it to that directory and activate it from the Plugin administration menu.