Nice idea, comrade.
www.sharedtalk.com-A networking site for language learners. You can make an account, customize your profile around your native language and ones you want to study. Has text and voice chat for practice.
http://lang-8.com/- Like Myspace/Livejournal for language exchange. You can make friends, customize your profile and join groups. You write "blogs" in the language you're studying, and other will correct your mistakes for you. Very useful to practice your grammar, syntax etc.
http://www.kidtaja.co.kr/-Korean website that hosts hangul typing games for children. Great if you're just learning to type Korean on your computer.
http://www.omniglot.com/-Huge index of hundreds of languages and writing systems. Has pages with summaries of different languages and links to websites specific to them.
http://www.zhongwen.com-Biggest online Chinese dictionary.
http://www.spanglishfun.com/-Another language networking site, but this time specifically for Spanish.
http://lomastv.com/land.php-Online video site, offering video immersion in Spanish. Videos have Spanish/English subtitles and different types of videos. *Costs a monthly fee*