I saw the following this week. I think they're all good reminders to proofread everything.

1. On a sign for a tutoring company...
    Times running out to enroll your child.

2. In an email from a co-worker...
    He maid me do it.

3. CNN News Scroll...
    Argentina and Chili sponsored...

4. In an email for an eNewsletter
    Sign up for the new addition of our eNewsletter.