baidu：Mozilla/5.0 (compatible; Baiduspider/2.0; +http://www.baidu.com/search/spider.html)
Google：Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)
Sogou：Sogou web spider/4.0(+http://www.sogou.com/docs/help/webmasters.htm#07)
Yahoo：Mozilla/5.0 (compatible; Yahoo! Slurp/3.0; http://help.yahoo.com/help/us/ysearch/slurp)
百度网页搜索 User-agent
Baiduspider
无线搜索 User-agent
Baiduspider-mobile
图片搜索User-agent
Baiduspider-image
视频搜索 User-agent
Baiduspider-video
新闻搜索 User-agent
Baiduspider-news
百度搜藏 User-agent
Baiduspider-favo
百度联盟 User-agent
Baiduspider-cpro
谷歌User-agent
Googlebot
MSN User-agent
MSNBot
有道User-agent
YoudaoBot
搜狗User-agent
Sogou inst spider
Sogou spider2
Sogou blog
Sogou News Spider
Sogou Orion spider
即刻User-agent
JikeSpider
搜搜User-agent
Sosospider
360User-agent
360Spider
百度爬虫，第二条为百度图片爬虫
Baiduspider+(+http://www.baidu.com/search/spider.htm")
Baiduspider-image
google爬虫，最后一条为google图片搜索爬虫
Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)
Googlebot/2.1 (+http://www.googlebot.com/bot.html)
Googlebot/2.1 (+http://www.google.com/bot.html)
Googlebot-Image/1.0
即刻搜索爬虫
Mozilla/5.0 (compatible; JikeSpider; +http://shoulu.jike.com/spider.html)
雅虎爬虫（分别是雅虎中国和美国总部的爬虫）
Mozilla/5.0 (compatible; Yahoo! Slurp China; http://misc.yahoo.com.cn/help.html")
Mozilla/5.0 (compatible; Yahoo! Slurp; http://help.yahoo.com/help/us/ysearch/slurp")
新浪爱问爬虫
iaskspider/2.0(+http://iask.com/help/help_index.html")
Mozilla/5.0 (compatible; iaskspider/1.0; MSIE 6.0)
搜狗爬虫,第三条为搜狗图片爬虫
Sogou web spider/3.0(+http://www.sogou.com/docs/help/webmasters.htm#07)
Sogou Push Spider/3.0(+http://www.sogou.com/docs/help/webmasters.htm#07)
Sogou Pic Spider/3.0(+http://www.sogou.com/docs/help/webmasters.htm#07)
搜搜爬虫
Sosospider+(+http://help.soso.com/webspider.htm)
网易有道爬虫
Mozilla/5.0 (compatible; YoudaoBot/1.0; http://www.youdao.com/help/webmaster/spider/; )
MSN爬虫
msnbot/1.0 (+http://search.msn.com/msnbot.htm)
百度和360验证过。
参考：
http://hi.baidu.com/romicboy/item/afc8d8d217278d5bd63aae22