Gadu Gadu
Gadu-Gadu is a Polish instant messaging client using a proprietary protocol. Gadu-Gadu was 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. Users send up to 300 million messages per day.
Your can use Gadu Gadu on your desktop computer with All-in-One Messenger.