Google Webmaster Tools now provides a single page where you can adjust the settings on your site.
The new settings page includes:
1. Geographic Target
2. Preferred domain control
3. Opting in to enhanced image search
4. Crawl rate control
Geographic Domain – tell Google if your website is associated with an even more specific area than your .com, .ca or .uk indicates.
Preferred Domain Control – Which domain do you want Google to crawl, the www (http://www.domain.com) or non www (http://domain.com) version.
Opting in to Enhanced Images -Allows you to use tools like Google Image Labeler to help improve indexing and search relevance.
Crawl Rate Control – Usually it is a good idea to let Google determine the crawl rate of your site but for larger, more advance sites you can let Google know if there are specific issues they need to address.