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.
Silicon Valley Dictionary - Urban dictionary meets Silicon Valley
SlangSite.com - SlangSite.
Urban Dictionary Random Word - Random word when you open a new tab in Chrome
InternetSlang.com - InternetSlang.
Words For That - the reverse-Urban Dictionary of the internet