I’m lazy when it comes to online dictionaries. I use answers.com because it’s automatically there when you type a word in google. I’m finally switching to wikitionary. Yes, I know that wikis are just user-created, inexact, consensus reality. But, it’s huge, fast and it feels like a living document. Even recently coined words have an entry, usually incomplete, but still something to point you in the right direction.
You can also find curse words in many many languages, slang and debate. Worth checking out.
Creative Creativity 