+=item C<is_ajax>
+
+Returns trueish if the request is an XML HTTP request, also known as
+an 'AJAX' request.
+
+=item C<type>
+
+Returns the requested content type (either C<html>, C<js> or C<json>).
+
+=item C<layout>
+
+Set and retrieve the layout object for the current request. Must be an instance
+of L<SL::Layout::Base>. Defaults to an isntance of L<SL::Layout::None>.
+
+For more information about layouts, see L<SL::Layout::Dispatcher>.
+
+=item C<cache $topic[, $default ]>
+
+Caches an item for the duration of the request. C<$topic> must be an
+index name referring to the thing to cache. It is used for retrieving
+it later on. If C<$topic> doesn't start with C<::> then the caller's
+package name is prepended to the topic. For example, if the a from
+package C<SL::StuffedStuff> calls with topic = C<get_stuff> then the
+actual key will be C<::SL::StuffedStuff::get_stuff>.
+
+If no item exists in the cache for C<$topic> then it is created and
+its initial value is set to C<$default>. If C<$default> is not given
+(undefined) then a new, empty hash reference is created.
+
+Returns the cached item.
+