This simply come out on my mind, I saw a lot site that with Sitemap and I think Google will love those site with sitemap, please spend some time on it and eventually you will see the result too.
For contents site, there are not software that can automate for us, although there are software that doing that, just that they will end up adding a lot of junk into your XML file which I don’t like. You still can use it, just that make sure you clean up before you upload into your host. Regarding the format, simple Google it from google.com and you will find a lot of them. Pick one of them and follow it.
For WordPress site, all you need to do is to install the plugin and basically you are done. One done, submit your sitemap to major search engines like Google.com (using webmaster tools), MSN.com and Yahoo.com. Each time you have any updates, all you need to do is resubmit the sitemap to the search engine.
I have noticed this, my site get index real fast if you have sitemap.xml file. Just a simple task and I think is worth to put some effort on it to get your site index fast. Thanks