Please enjoy this smattering of Word of the Day sites and pages: OED (RSS), Wordsmith (RSS), Wordnik, The Free Dictionary (RSS), Merriam-Webster (RSS), WordThink (RSS), Urban Dictionary (RSS), Macmillan (RSS), NY Times Learning Network Blog (RSS), Scrabble, Wordsmyth (RSS), Easy Speak (Toastmasters), Wiktionary, Wiktionary "Foreign", OLDO (RSS: Chinese, French, German, Italian, Russian, Spanish, all in OLDO), Arabic (RSS), Japanese (RSS), Nahuatl, ASL, History, Geology, Theology (RSS), and Sesame Street (not daily, unfortunately).
Wordchamp lets you view foreign-language web pages with definitions in your language as mouseovers (registration-only). [more inside]
Wikiwords is a collaborative project to create a dictionary of all terms in all languages.
The Encyclopedia of Cajun Culture features everything from Acadiana to Zydeco. Two of the more interesting entries I've found are the Un-Cajun Committee and the unknown to me genre of Swamp Pop
Do Most Of You Yanks Really Understand What The Brits Here Are On About? Although the cultural mistranslations are probably more a question of tone and habits of irony and understatement, Jeremy Smith's online American·British British·American Dictionary, to be published next September, might be of some assistance. Although I still prefer Terry Gliedt's older but pithier United Kingdom English For The American Novice and even Scotsman Chris Rae's English-to-American Dictionary. Here's a little BBC quiz to test your skills. It seems that Canadians, Australians and [another cute quiz coming up!] New Zealanders are the only Metafilterians to completely capture all the varieties of English usage here. Perhaps it all comes down to the fact that non-U.S. users know much, much less about England, Scotland, Wales, Ireland, Canada, Australia, New Zealand et caetera than vice-versa? Does anyone else get the occasional feeling we're not exactly speaking the same language here?