http://www.vocabtest.com/

http://www.apstrategies.org/vocab/individuallessons.htm

Anyhow – there are some fun ‘improve your vocab and spelling’ type websites that you could turn into lessons:

http://www.sentex.net/~mmcadams/spelling.html

http://www.vocabulary.com/index.html

Some recommended wordlists from dictionary and university sites:

http://www.houghtonmifflinbooks.com/booksellers/press_release/100words/

http://www.eduplace.com/rdg/hmsv/8/homeconnection/index.html

http://www.adultspellingbee.com/

You have to sign up here, but there’s a pretty extensive bunch of worksheets, etc.:

http://www.edhelper.com/spelling.htm

There is also a great list of inexpensive books for adult spellers here:

http://astore.amazon.com/betterspelling-20

Best of luck!!

Try searching for something like _improve your spelling_ and see what comes up.