Appending XML to File

I was wondering if anyone had used XML in a logging context.

    Have you wanted to append XML to file, or store XML events to
    file? How did you do this and manage to keep the document well
    formed?
    
    1. Create a directory structure contianing a document for each
       event. 

    2. Create a file that contains one document after another, each
       representing an event..

    3. Seek to the start of the last element, overwrite with 
       event and new element.

    Option 1 sounds unwieldy, option 2 creates a peculiar file, and
    option 3 sounds fragile.

    Insight is much appreciated.

--
Alan Gutierrez -