Monitoring and managing the health of .NET applications during their lifecycle is not a small task. Fortunately, AVIcode, a Microsoft partner based in Baltimore Maryland, provides a .NET Management Pack that extends the application monitoring capabilities of Operations Manager 2007 and make the process of minitoring and managing .NET applications much more effective. You can find more infomation on AVIcode's solution at http://www.avicode.com/msft.
For general guidance on how to create manageable applications, try the Visual Studio Management Model Designer (VSMMD) available at http://www.codeplex.com/dfo/Release/ProjectReleases.aspx?ReleaseId=2770 Note that VSMMD requires Visual Studio 2005 Professional Edition (or Visual Studio 2005 Team System).
For AVIcode's solutions for other Microsoft server products such as BizTalk, SharePoint and SQL Server Reporting Services, visit
AVIcode BizTalk Server 2006 Management pack
AVIcode Office SharePoint Server 2007 Management Pack
AVIcode Reporting Services Management Pack