I've talked at some length in this blog about the importance of shimming your managed add-in so it can live in its own appdomain and not do damage to other add-ins. Also, while I'm on the topic, please don't force a particular version of the CLR--always load the latest version available of the CLR.
Anyway, it required a bit of rocket science to actually build the add-in shim.
Fortunately, Andrew Whitechapel, Misha Shneerson, and Siew Moi Khor have just published an article and a wizard to make it super easy to build your shim for your managed add-in.
Check it out at http://msdn.microsoft.com/office/default.aspx?pull=/library/en-us/dno2k3ta/html/ODC_Office_COM_Shim_Wizards.asp
I'm really excited about this, I've been working on a managed add-in for Outlook and I'm going to use this tool to build a shim for it. I'll let you know how it goes.