Someone has posted an archetype recently, it actually looked not bad (I didn't try it though) so if you search the forum you should be able to find it.
There is also JBSEAM-2371 which has a few prototypes.
Hope this helps...
Some developers at Know IT Objectnet have created a template Seam,Maven2 project template.
The code also includes Mavenized examples from Seam In Action by Dan Allen.
The project includes profiles for: prod and dev settings, different databases such as mysql,mssql,postgresql, as well as parameterized setup for dependencies. There are different profiles for application servers, and so far it has been tested deployed on JBoss AS 4.2 and 5.1
The code can be checked out at http://code.google.com/p/seam-maven-refimpl/ and a tutorial on how to get started can be found at http://www.glxn.net/seam-maven-refimpl/doc/tutorial/