Who or Whom?

Callie asks in a comment about this big headache for English learners. It gives me a good reason to mention the "Google Search" on this site.

If you scroll down a little, you'll see the search window in the right-hand column. Type in "whom" and you'll get links to all my uses of the pronoun (on all my blogs!).

Check the first two or three links to this blog, and I hope the posts will answer your question.