Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1)
Opera/9.20 (Windows NT 6.0; U; en)
Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)
Googlebot/2.1 (+http://www.googlebot.com/bot.html)

http://www.useragentstring.com/pages/Googlebot/