You can do it easily with many of the blogs, either with a service
such as Sailblogs. sailmail and Xgate plus others will automate the process of posting
position information to sailblogs.
or you can set up a site using a content manager such as Wordpress and use one of the Google
Or you can mashup the google
maps code yourself.
I have been playing with a setup using Wordpress and some of the google maps plugins. I just send an email
that I have imaginatively called position report
Wordpress filters can choose not to display the position report post but the google map on the site will be updated.
I haven't played with it yet, but I think I should be able to use sailmail which can automatically include the position in each email
. Some of the wordpress plugins can strip position information and produce a Google map.
There were some threads on here a recently on Wordpress and the various map plugins; just do a search.
If you can already email from the boat, and get GRIBs in daily then you can provide a position update each time you do a send and receive of your mail at virtually no cost.