Diction for Grammar and Writing Students
Diction deals with wrong words, confusable words, and the "that's just not how we say it" issue. Here are some great pages to help.
Common Errors in English
The largest list of all
Words that are Often Confused
A truly enormous list
A brief summation of some biggies
Bedford St. Martins
Wrong Word Errors and Exercises (If you log in)
OWL Online Writing Lab
Another thorough listing
Homographs: Look alikes pronounced differently.