Useful / Interesting? Casual vs Formal usage...
I'm not sure this is useful or accurate...but would be interested in a couple other people taking a look.
The dictionary page has had the "Usage Frequency" indicator for a while. This tells how common a word is from our corpus of 24 million words. This can be really useful to determine which of several verbs, for example, are more commonly used.
I took it a step further and ranked all words based on formal sources, and then ranked them again based on casual sources...hopefully to give a further indication of whether a word is considered more formal or more casual.
The script ranks all words by frequency using both formal sources (mostly newspaper articles) and informal sources (a combination of over 100 hours of transcribed audio, internet comments, and amateur fiction writing) to roughly determine whether a word is used more frequency in casual or formal contexts...
On a word's full dictionary entry page, it will show the comparison just below the frequency indicator section...something like:
"This string is used more frequently in casual content than formal content."
...then you can click on the "?" icon to see more details about how each is ranked.
I'm not sure how useful this will be...or how accurate...but I thought I'd put it out there, in case others are interested!