Under 'Google/SEO' choose 'Google Tracks'
This report will show the last 500 pages that Google had been to and when they had been there.
Some of the visits will be a single page scan, while others will be deep scans.
The single page scans generally only view the front page of the site, looking for changes. If changes are noticed, and if the changes involve links, a deeper scan will be scheduled for the googlebot.
Adding new articles and keeping the forum postings on the front page is important because it keeps the front page fresh. The more often you update your site, the more often Google will visit and will do deep scans of the site.
To see which phrases people are using to get to your site or where they are coming from, refer to 'Todays Referrals'. This report is found under 'Reports'.