FYIFound these 2 on Wikipedia... the user numbers speak for themselves! Facebook isn't the only sherriff in town when it come to Ortsbo application!
Tencent QQ, generally referred to as QQ, is the most popular free instant messagingcomputer program in Mainland China. As of September 30, 2010, the active QQ users accounts for QQ IM amounted to636.6 million[1], possibly making it the world's largest online community. The number of simultaneous online QQ accounts exceeded 100 million[2]. In October 2010, QQ.com ranked 9th overall in Alexa's internet rankings just after Twitter ranked 10th.[3] The program is maintained by Tencent
Gadu-Gadu (Polish for "chitchat"; commonly known as GG or gg) is a Polish instant messagingclient using a proprietaryprotocol. Gadu-Gadu is the most popular IM service in Poland, with over 15 million registered accounts and approximately 6.5 million users online daily. Gadu-Gadu’s casual gaming portal had some 500,000 active users at the end of March 2009.[1] Users send up to 300 million messages per day.[2]
Gadu-Gadu is financed by the display of advertisements. The developer is based in Warsaw, Poland.[3]