ebuddy is your web based online messenger for MSN, Yahoo, Goggle Talk, MySpace and AIM (AOL). Whether you're at home, school, work or travelling; with eBuddy you can chat online everywhere, at any time. eBuddy is available as a web based and mobile version. eBuddy means no downloads, no installation of software or upgrades and no registration. Best of all it's free!
Chinswing is a global message board where anyone can add voice messages to ongoing topical discussions. Share your personal interests or hobbies, debate hot issues or find answers to questions. 
Gabbly is an online chat service that allows you to chat in any website. It's free for personal and commercial websites. Just add your domain name after gabbly.com/ and you can chat live on your website.
Meebo is a web based instant messaging service that allows you to chat directly in your browser as if you where using your own IM client.