Here's a fantastic example of an ad that uses ethos, pathos, and logos:

Ethos (credibility): Star Wars, yo.  By beginning the ad with Darth Vader walking down a hallway with the theme music in the background, they're immediately connecting the audience to something they know and trust (in most cases, even if they haven't seen the movies.)

Pathos (emotional appeal): Aww . . . it's a little kid dressed up like Darth Vader.  That's so cute!  And he's trying to "Force" everything and it's not working - hilarious! (This commercial is seriously sweet and funny.)

Logos (logic): This is all about showing you the actual product and what it can do, and in this case, it's the car. They make sure to show the audience different views of the car itself (front, side, interior), and even that it has remote ignition.  It's also about facts and figures.  The whole commercial suggests that this car is good for small families (parents, son, daughter, dog).  It also gives you the price at the very end, and it seems pretty affordable to the target audience (which isn't high school kids).