Gadu-Gadu, also known as GG, is a Polish instant messaging client that's been very popular in Poland for years (Gadu-Gadu simple means 'chit-chat' in Poland). While many other messengers exist across the Internet, Gadu-Gadu is a well-balanced messenger that has developed a huge assortment of features over its 19 years of life, making it so much more than a messenger. Gadu-Gadu does nearly everything you could ever want for a messenger and then some, turning it into a robust and well-rounded messenger that does so much more than share essential messages.
For starters, it has a nice built-in online radio via Open.fm. It also has a free e-mail client built-in as well, in addition to an online file storage system, and even has connections to social media, such as Facebook or Twitter, or games like Farmville via a casual gaming portal.
But the most important aspect is the messenger itself, which is also full of features. It includes over 150 emoticons and allows uploading custom status messages. It also supports file sharing and grouping contacts and will let you speak over VoIP, or even send SMS messages. Chats can be sorted quickly into tabs, so you never lose track of which conversation is which.
Similar to ICQ, users are identified by serial numbers, but Gadu-Gadu allows users to add personal information that shows up in a publicly searchable directory.
For the record, this is a Polish messenger, and most users are Polish, but with language options available for both Polish and English, this does work well as a messenger for English speakers or Polish-Americans. Gadu-Gadu is available for almost all popular desktop OSes such as Windows, Mac, or Linux, or even mobile support for Android, iOS, Windows Mobile, or even Blackberry. As a downside, Gadu-Gadu is supported by ads, so you will get the occasional ad while chatting, but they don't seem to be overly intrusive and do not inhibit your ability to chat.
With all that you get from this messenger, it's hard to top, and don't let the Polish aspect fool you. This is still a strong messaging client for any English speaker, who wants to chat, listen to online radio, access e-mail, and store files all in one app, and all of this for free.
Feature rich messenger that connects to Internet radio and social media