A
couple of my colleauges who as far as I know have all their life worked with ASP
(mind you not ASP.NET, just the now aged ASP) were trying to dip their feet into
SharePoint. One of them developing a paticular WSS site kept insisting on the
need for an asp include file to create a bit of jazzy navigation.
Now as you know SharePoint does not allow include
files. So I proposed for all the links to be on a WSS list and then
render the navigation by means of DVWP. Yes this can be done, but to create some
Jazzy UI effects its a bit tedious. For quite some time I was playing around
with the DVWP trying to recreate the Jazzy Naviagation and tollerating all the
whining going on around me. 
Then it suddenly dawned on me. You could actually
sort of emulate ASP include files using the DVWP, at least for the current
requirement. You see in this paticular requirement the include
file only contains HTML and JavaScript. The purpose of the include file was
to have a single location to edit if any of the navigation links change
and a single location to edit to change the presentation aspects of the
navigation. And if you are thinking how about replacing the default header with
an alternate header, that wouldnt do, because this is a left navigation that
would be used in addition to the default header. And if you are thinking just
write a WebPart, that would take too long.
The fastest way of emulating the above is to dump
the HTML that would make up the Navigation into a CDATA section of an XML file.
Host the XML file on the WSS Site. Setup a DVWP to use the XML file a
DataSource. Render the CDATA element with enable content escaping = Yes, and
voila! you are done.