You could be seeing any of these:
66.249.71.148 - - [10/Apr/2012:10:33:11 -0500] "GET /index.php?topic=13469.20 HTTP/1.1" 200 9698 "-" "Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)"
66.249.71.148 - - [10/Apr/2012:10:33:28 -0500] "GET /index.php?topic=13469.25 HTTP/1.1" 200 9686 "-" "Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)"
180.76.5.140 - - [11/Apr/2012:20:53:16 -0500] "GET /index.php/topic,13469.10.html HTTP/1.1" 200 8836 "-" "Mozilla/5.0 (compatible; Baiduspider/2.0; +http://www.baidu.com/search/spider.html)"
180.76.5.151 - - [12/Apr/2012:11:46:56 -0500] "GET /index.php/topic,13469.msg166916.html HTTP/1.1" 200 8855 "-" "Mozilla/5.0 (compatible; Baiduspider/2.0; +http://www.baidu.com/search/spider.html)"
180.76.5.187 - - [12/Apr/2012:22:50:00 -0500] "GET /index.php/topic,13469.msg166912.html HTTP/1.1" 200 8854 "-" "Mozilla/5.0 (compatible; Baiduspider/2.0; +http://www.baidu.com/search/spider.html)"
199.21.99.118 - - [13/Apr/2012:12:34:09 -0500] "GET /index.php?PHPSESSID=eiiral94ogq1gh42iipr0em906&action=ignore;u=150;topic=13469;msg=172067 HTTP/1.1" 200 6694 "-" "Mozilla/5.0 (compatible; YandexBot/3.0; +http://yandex.com/bots)"
199.21.99.118 - - [15/Apr/2012:01:17:39 -0500] "GET /index.php?PHPSESSID=eiiral94ogq1gh42iipr0em906&action=ignore;u=150;topic=13469;msg=172067 HTTP/1.1" 200 6722 "-" "Mozilla/5.0 (compatible; YandexBot/3.0; +http://yandex.com/bots)"
180.76.5.175 - - [15/Apr/2012:19:37:31 -0500] "GET /index.php/topic,13469.30/wap2.html HTTP/1.1" 200 1723 "-" "Mozilla/5.0 (compatible; Baiduspider/2.0; +http://www.baidu.com/search/spider.html)"
208.115.113.82 - - [16/Apr/2012:03:31:56 -0500] "GET /index.php/topic,13469.0/all.html HTTP/1.1" 200 172857 "-" "Mozilla/5.0 (compatible; Ezooms/1.0; ezooms.bot@gmail.com)"
199.21.99.118 - - [16/Apr/2012:07:04:51 -0500] "GET /index.php?PHPSESSID=eiiral94ogq1gh42iipr0em906&action=ignore;u=183;topic=13469;msg=172052 HTTP/1.1" 200 6763 "-" "Mozilla/5.0 (compatible; YandexBot/3.0; +http://yandex.com/bots)"
180.76.5.140 - - [17/Apr/2012:07:53:43 -0500] "GET /index.php/topic,13469.0.html HTTP/1.1" 200 8826 "-" "Mozilla/5.0 (compatible; Baiduspider/2.0; +http://www.baidu.com/search/spider.html)"