Slang
Linguistics
Idioms
Proverbs & Quotations

Slang

American Slanguages
http://www.slanguage.com/

Idioms

Color-related Idioms(P.M. Eberz.)
http://www.ojohaven.com/fun/color.idioms.html

ESL Cafe's Idiom Page
Extensive listing.
http://www.eslcafe.com/idioms

ESL Cafe's Phrasal Verb Page
Many phrasal verbs, complete with definition and samples.
http://www.eslcafe.com/pv

Toon in to Idioms
Cartoons and audio from Adam Rado.
http://www.elfs.com/2nInX-Title.html

Linguistics

Constructed Human Languages
http://www.quetzal.com/conlang.html

Ethnologue Database
http://www.sil.org/ethnologue/

Human Language Page
http://www.June29.com/HLP/

Linguistics Resources on the Internet
http://www.sil.org/linguistics/

On-line Phonology Course
An online phonology course including sound.
http://www.stir.ac.uk/epd/celt/staff/higdox/stephen/phono/phonolg.htm

TPR: Total Physical Response
http://www.tpr-world.com/