Many people like myself don't completely trust the various WordPress spam filters and elect to moderate all comments before they show up on the actual site, which ends up flooding your email with moderation notices.
In my quest to keep a clean inbox, I've created a small application that notifies me directly on my desktop when new comments come in to the moderation queue. It accesses the WordPress XML-RPC API by means of a small Wordpress plugin that I've created.
First, screenshots... notice the icon in the system tray. You can quickly launch your comment moderation page via the right-click menu.
When there are new comments, you'll see this little message pop up, and then the icon will change to some random icon alert icon I found somewhere. If you click on the text it will take you to the moderation page.
The settings page is about as simple as it gets. Just enter in the base url of your blog and it'll figure out the right path to xmlrpc. (unless you've renamed xmlrpc.php, in which case this won't work at all)
The password is encrypted and stored in the xml file in the same directory. Don't assume this is entirely secure, however. Remember that all XML-RPC utilities are insecure unless you are using SSL or something like that.
Naturally, I don't guarantee anything with this software, and am not responsible if it breaks windows, melts all the spinach in your freezer, or dyes your hair green.
I will be releasing the source code to this utility shortly, since it was based partially on the open source Google Reader Notifier.
Technical Note
The WordPress plugin implements a new XML-RPC method called geek.getCommentModerationCount. This method could be called by any other language that can handle XML-RPC, so the WordPress plugin could be used by itself.
This means somebody could easily write an application for Linux or OS X to call the same method. (hint) It would even be possible to implement other WordPress functions this way, through a plugin.
Take a look at the WordPress plugin for the details, it's very simple.
WordPress Support Plugin Installation (Required)
The WordPress plugin should be copied to your wp-content/plugins/ folder in your Wordpress installation, and then activated in the Plugins panel. I've tested with WordPress 2.0 and WordPress MU.
Notifier Installation
Unzip the file and put it into a directory where you'd like to keep it. If you want it to run on startup, you'll have to create a shortcut to it in your startup folder.
Once you launch the application, you can configure the settings and it should work.
System Requirements
.NET 2.0 Framework
Support
Leave feedback in the comments. If you have issues with this application, you can always ask your question on the forum.
Download WordPress Notifier