This mind-blowing TEDTalk by Deb Roy called The Birth of a Word shows his project recording his family's life in their home for 5 years and how he was able to track the language development of this newborn son as he learned to speak. Roy also uses spectacular mapping techniques to show various clusters of words and movement throughout the apartment.
Its a long video, but well worth your time.
Development of words beyond single individuals is still occurring every day. New words are created in our society, and sometimes adopted as official words. There are even Word of the Year competition based on their use or creation within that year. Here's Urban Dictionary's 2010 Word of the Year Top 10. They are more just funny popular sayings...but you get the idea.
Studies have shown that the use of color words in language develop in similar orders no matter where or when this occurs. If a language only has two words for color, it will always be for black and white. If they have a third word, it is always for red. After that, the most common color words are for green and yellow. Sometimes however, a remote tribe in the desert might have 5 words for the color red before ever having a word for the color green.
A fun project by the Oxford Dictionary is called Save the Words. Its an initiative to get some words back into common language that have faded out of use. You can pan around the page to see all these crazy words you've never heard of (if you sound is on, you'll hear that they are in fact begging you to choose them). If you click a word, you can see its definition. You can also create an account and adopt a word. You must swear "to use the word in conversation and correspondence as frequently as possible to the best of your ability" :)