the follow SSI illustrates the versitility of the new regex features of mod_include. Throw it in a HEADER.html, turn on the INCLUDES filter, and play :)
<form> Show me a <select name=F> <option <!--#if expr="$QUERY_STRING = /F=0/" -->selected <!--#endif --> value=0> Plain <option <!--#if expr="$QUERY_STRING = /F=1/" -->selected <!--#endif --> value=1> Fancy <option <!--#if expr="$QUERY_STRING = /F=2/" -->selected <!--#endif --> value=2> Table </select> list sorted by <select name=C> <option <!--#if expr="$QUERY_STRING = /C=N/" -->selected <!--#endif --> value=N> Name <option <!--#if expr="$QUERY_STRING = /C=M/" -->selected <!--#endif --> value=M> Date Modified <option <!--#if expr="$QUERY_STRING = /C=S/" -->selected <!--#endif --> value=S> Size <option <!--#if expr="$QUERY_STRING = /C=D/" -->selected <!--#endif --> value=D> Description </select> in <select name=V> <option <!--#if expr="$QUERY_STRING = /V=0/" -->selected <!--#endif --> value=0> Normal <option <!--#if expr="$QUERY_STRING = /V=1/" -->selected <!--#endif --> value=1> Version </select> <select name=O> <option <!--#if expr="$QUERY_STRING = /O=A/" -->selected <!--#endif --> value=A> Ascending <option <!--#if expr="$QUERY_STRING = /O=D/" -->selected <!--#endif --> value=D> Descending </select> order, matching <input type=text name=P <!--#if expr="$QUERY_STRING = /P=([^&]*)(&.*)*$/" --> value="<!--#echo var="1" -->" <!--#endif --> > <input type=submit value="go" > </form>