Other
Suber & Thorpe: An English Homophone Dictionary
This website provides a simple definition of homophone as well as a very long list of homophones, organized alphabetically.
Quia
Quia: Conjunctions & Interjections
Twelve sentences in which students are asked to fill in the box by choosing the correct word: to, two, or too. Correct answers are provided for any missed questions, and a final score is tallied at the end of the exercise.