Yesterday I wrote about creating customer login block in our free html block module. The main disadvantage of this method is fact, that login form don't disappear after login. Now i want to show you little workaround. To achieve this you have to edit the html.tpl file located in the html box module directory. 

Open this file, you've got there only one variable:

{$htmlboxbody}

change this code to:

{if !$logged}
{$htmlboxbody}
{/if}

then save changes to this file. What code above mean? It mean that if user isn't logged - the script will show the content that you pasted into "code" field in the html block module configuration page. That's all!