bestvpnservice.com - Chinese Firewall Test

Check whether your website is accessible from China or not. This test will give you results from 5 different locations of China.

greatfirewallofchina.org - Great Firewall of China

Test a website address and see if it is blocked in China.

viewdns.info - Chinese Firewall Test

Checks whether a site is blocked by the Great Firewall of China. This test checks across a number of servers from various locations in mainland China to determine if access to the site provided is possible from behind the Great Firewall of China.

websitepulse.com - Proxy Checker - Website Test behind the Great Firewall of China

Test any website in real-time to check if it is accessible from China. The test shows if your website is available in Shanghai, Beijing, Guangzhou and Hong Kong. Website Test Great Firewall of China - Golden Shield Project.

watchmouse.com - WatchMouse website monitoring service - Ping - IPv6 now supported, give it a shot!

Ping a server or web site using our network of over 30 monitoring stations worldwide.

webkaka.com - 網速測試,測網速,網速檢測,網站速度測試—卡卡網

國內最專業最權威的在線網速測試及網站速度檢測網站，遍及國內各省和國外的幾十個網速測試及網站速度檢測點，包括電信、網通、聯通、移動、長城寬帶、教育網等線路，即時測試本地的網絡速度，測試網站在全國各地和海外的打開速度。

ping.chinaz.com - 多個地點Ping服務器 - 站長工具

通過該工具可以多個地點Ping服務器以檢測服務器響應速度。

speed.linkhelper.cn - 網站速度測試網站速度檢測網站速度探測-站長幫手網

測試各個地區訪問你的網站的速度，同時返回網站的狀態。以便站長瞭解自己的網站是否全國各地都能正常訪問。

參考：
whatblocked.com - 列出大陸封鎖了哪些國外知名網站
zh.wikipedia.org - 防火長城 - 維基百科，自由的百科全書