how to get current URL in SharePoint?

[jvoronsky]

I am using SharePiont Server 2007 Enterprise with Windows Server 2008 Enterprise, and I am using publishing portal template. I am developing using VSTS 2008 + C# + .Net 3.5. I am using left navigation area (in SharePoint terms, it is also called current navigation area), and each item in the left navigation area maps to either a sub-site or a specific URL (i.e. clicks the item in left navigation area will display content of welcome page of the specific sub-site or the content of the specific URL in the main content area on the central area).I want to know which URL is displayed on the main content area when an item in the left navigation area is clicked. Any samples to make a reference?thanks in advance,George