Vocabulary Development

Synonym Toast
Catch the toast slices that have synonyms for the word displayed.
Robo-Bee
Fly the bee into the correct word to complete the phrase or sentence. The words include synonyms, antonyms and homophones. Each time you replay you will get a variation on the questions so you can play this more than once.
BIGbot
Feed the robot the correct synonym or antonym for the word given.

Online Activities

Thesaurus links can be found in Reference Section.
Spelling and Vocabulary - Houghton Mifflin
This site has printable word finds, letter and word games and word puzzles at eight different levels. Each printable is a PDF file.
Vocabulary University
This site is a little difficult to navigate around and rather clustered but there is still a lot of good interactive content to develop vocabulary. There is a note on the site that the design is about to be upgraded.
Word Central Daily BuzzWord
There is a word of the day on this page which you can subscribe to using RSS if you want to.
New York Times Student Word of the Day
Presents a word and examples of usage for the word as well as the word in context in a newspaper article.
Yahoo Education Word of the Day
There is a definition, example of usage, synonyms and links to the word in online dictionaries and thesaurus.
WordThink Word of the Day
Focus's on useful words rather than obscure and pretentious words.

General Vocabulary Resources