ManyThings.org - ManyThings is a multiplatform and user friendly application for students of ESL or EFL to learn the meanings and definitions of different terms and phrases.
Urban Dictionary - Urban Dictionary is a Web-based dictionary of slang words and phrases.
SlangSite.com - SlangSite.
Hinglish Dictionary - HinglishDictionary.com is an archive of user submitted Hinglish words. Users can register and create accounts and add new words, that must have a touch of Hinglish language in it.
InternetSlang.com - InternetSlang.
Wiktionary - Open Source wiki-dictionary by the Wikimedia foundation