Fix any invalid code

There are generally five main problems with sites that can be fixed easily - in many cases with a simple global change across the entire site. The most common problems are:

Incorrect or missing Doctype
<!doctype html public "-//W3C//DTD HTML 4.01 Transitional//EN">
No character set
<meta http-equiv="content-type" content="text/html; charset=iso-8859-1">
Missing invalid or unquoted attributes
(width=16 should be width="16")
Four horsemen of the apocalypse
<body topmargin="0" leftmargin="0" marginheight="0" marginwidth="0">
Untyped JavaScript Code-blocks
<script language="JavaScript" type="text/javascript">

For more info, go to Validating Australian Museum Online and the results of these validations.