On the Scripps National Spelling Bee website, www.spellingbee.com, you can sign up for free resources to help you prepare for the Spelling Bee, including additional word lists and extra practice.

http://spellingbee.com/wordclub
Another great site I found provides Spelling Bee practice by combining spelling, vocabulary, and reading skills.
https://www.learner.org/interactives/spelling/
Another fun, interactive spelling game is
http://www.arcademics.com/games/spelling-bees/spelling-bees.html
Dictionary games:
http://myspellit.com/
http://www.wordcentral.com/
http://www.merriam-webster.com/
I have played all these games myself! They are all fun and challenging, and there is something for every level.
Post some comments about which practice activities you used. What did you think of these activities? Which ones are the most helpful? What other ways are you practicing for the Spelling Bee?
Happy Spelling!