Is there a way to mass mail all the members of my site? We will be switching to WaR and I want to send an email to everyone who played with us.

Click your Admin link, go to General Settings and look for Newsletters. Just keep in mind that some people (like me) keep more than one email address, and the one they signed up to your site with might not be the one they use/check regularly. I always copy/paste Newsletters to the forums for this reason.