I assume that I should can type echo "<B>$foo</B>", I should be able to type echo "<B>$$reference_to_foo</B>"

This doesn't work...

Also...

echo "Hi! $$var";

should be equivalent to 

echo "Hi! " . $$var;

unless I am mistaken...

Included below is a snippet which gives an example...

/*************************************************/
<PRE>
<?
$bob = "Bob Smith";
$variable_name = 'bob';
$variable_value = $$variable_name;

echo "These should all be the same\nBut... they aren't...\n\n";
echo "\"$variable_value\" == \"$$variable_name\"\n";
echo "\"" . $variable_value . "\" == \"" . $$variable_name . "\"\n";
echo "\n";
print ("\"$variable_value\" == \"$$variable_name\"\n");
print ("\"" . $variable_value . "\" == \"" . $$variable_name . "\"\n");
?>
</PRE>
/*************************************************/
Produces:
These should all be the same
But... they aren't...

"Bob Smith" == "$bob"
"Bob Smith" == "Bob Smith"

"Bob Smith" == "$bob"
"Bob Smith" == "Bob Smith"
/*************************************************/