Tony,
I have seen this one, but not used it:
- http://www.letscreate.dk/letscreate/?q=node/1
Look slike you can save the track and send them by email after you are done.

If you want to use it like a tacktick, then you might consider buying a waterproof case. I have seen these:
- OverBoard Waterproof Case for iPhone
- http://www.pelican.com/cases_detail_specs.php?Case=i1015

I'd be interested in your feedback if you get to try either.

GPS action replay is a great free tool.