All three are free and relatively easy to set up, and will help you bring in and track traffic to your site.
1. Google Analytics
Analytics is a free monitoring tool for your website, tracking the what-where-when of viewers coming to your site. Hits are recorded in terms of unique viewers, returning viewers, how many times certain pages are viewed, and how long users spend on your site. The geographical report graphically shows where your viewers are in the world. Entry points are monitored, both in terms of the page people arrive at, and how they arrived at your site - directly or from referring websites. Search engine statistics tell you what keywords people are using to find you and from which search engine.
For example, I know that in the last month I’ve had 572 visits, 77 of which were from the US and 64 from Australia. The average viewer spend 5 minutes on my site, and 90% of them were first time viewers. 27% came from a referral site, the most popular of which was Ninjaman. 12% came from search engines - the most common search being ‘adam searle’ - with Google being the most useful to me. Very useful software.
If like me your website or blog is based on Wordpress, try the Google Analytics Plugin for Wordpress.
2. Google Sitemaps
Sitemaps is a tool designed to aide google and other search engines in the navigation and indexing of your site. Using the tools provided on their site, you generate a sitemap.xml file that is then placed on the root level of your site. Search engines (other than google too) find this file and then have a better idea of all. You can read more about the theory behind sitemaps here. Additionally the Google Sitemap interface gives an insight into Googles record of you, and which sites link to you. The PageRank system that google is based on favours other, preferably reputable sites linking you - so this is useful in building relationships with key partners.
There is an excellent plugin for Wordpress that generates a Google Sitemap file, puts it in the right place, and notifies Google that you have updated your sitemap. Check out Google Sitemap Generator.
3. Google Adsense
Adsense is Googles advertising platform, enabling you to easily add a revenue source to your site. While I dont use this here, over at ninja-man.com we generate a healthy revenue stream that covers bandwidth costs etc involved in hosting the game. You’ll want to be bringing in at least a thousand views a month in order to make it worthwhile hitting your users with ads.
Check those out, and happy blogging!