After searching tirelessly I came upon this site and it is absolutely AWESOME.  Parents, teachers, and children can input spelling lists that are then turned into list specific activities.  Children can practice spelling their own words from school, hear them used in a sentence, and then play games using just those words.  Did I mention that you can also generate printables that use only those spelling words as well.  My kisd love Spelling City!  They don't even mind the sheets that I generate that require them to write and rewrite the words, because they think it is just so COOL.