When developing or debugging Albatross applications, one of the things you need to get right is when variables enter
and leave the so-called "local context", and what values they have.  Debugging this can be tedious, so I wrote a 
simple macro that I can call from any template that will show the name and value of all the variables currently in the ctx.locals namespace.
{{{
<al-macro name="showcontext">
    The current local context is:
    <ul>
      <al-for iter="ctxiter" expr="locals().keys()">
        <li><al-value expr="ctxiter.value()"> = 
            <al-value expr="locals()[ctxiter.value()]">
            </li>
      </al-for>
    </ul>
  </al-macro>
}}}

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This could be turned into a custom tag which only outputs data when something in the context or application is set. I wrote a JSP tag that dumped the request and session attributes to the page and it was very useful, especially for watching session usage.
-- Matt