SpellingCity is one of the most popular and my favorite site around for all things Vocabulary & Spelling. This is an excellent place for educators to browse or create word lists and even incorporate them into educational games. Also, there is a free mobile app (iOS/Android) that integrates w/ the site for practicing Spelling/Vocab.
I highly recommend checking out SpellingCity by clicking here!!!
*SpellingCity is an advertiser of Technology Tidbits.