Count users online with Sitecore OMS

When you have a web application, you might want to know how many users are currently online. If you have visited some of web online forums you can see (usually on the first page) the number of currently online users.
This information might be also used to postpone some website jobs if there are too many users online, etc.
How do we know / count how many sessions or users are currently connected to our website in Sitecore?

Windows Live Writer Integration for Sitecore

Windows Live Writer is a great tool for blogging. It is simple, fast, and can be customized using plugins written in .NET. You can have web-based interface for adding your blog or articles, but integration with desktop client will not be superfluous as it provides a lot of benefits.
 In this post I'll show how to integrate it with Sitecore CMS using MetaWeblog API -  an application interface  that enables weblog entries to be written, edited, and deleted using web services.

Integration can be divided into two parts:

1. Implementing MetaWeblog API service members 
2. Creating and configuring various handlers that will tell Live Writer how to find and use our service