Here are the 3000 most commonly used words in the English language in order of frequency of use. View them in groups of 100.

Kids in grades K-5 can practice making words with prefixes, suffixes, and other compound words.  There are ten games to choose from.

Below each of the prefix and suffix games is a list of prefixes or suffixes and their meanings.  The games have a lesson option, followed by several gameplay options.  Some of the games are multiplayer.

Greek and Latin Roots provides the base, origin and meaning of Greek and Latin root, prefixes and suffixes.  List is in alphabetical order by base word.

Kids in grades K-3 help Spelling Spellican practice spelling Dolch Sight Words.  You pick a level from pre-primer to third grade, or a combination of all.

To play the game, put the letters in the correct order to spell the word spoken.  You can ask for a hint.  Sometimes you have to feed the octopus a vowel after you spell the word.

From site:

Build Vocabulary through Word Games:

• Snonym Toast – How many synonyms can you grab from mid-air before the time runs out?
• Rhyme Time – Solve these rhyming riddles!
• Funny Pages – Stop by for cartoon captions and word games galore!
• Spelling Wizard – Make your own Word Search or Spelling Scramble!

This is a Flash-based game.  You must add a flash emulator, such as Ruffle, to your browser to be able to play it.