Company: LG Electronics, Englewood Cliffs, N.J. Agency: N/A Market: IT managers Quick chase: Wedged on a bookshelf is the razor-thin LCD Flatron computer monitor from LG Electronics. It's a brilliant way to demonstrate how thin the product is. We suppose there's a small chance that the reader wouldn't notice the monitor on the bookshelf. But for those who may have missed it there, LG provides a row of thumbnail images of the monitor. Copy introduces other product attributes, such as a picture-enhancing chip for better color and contrast as well as a three-year warranty. It ends with a call to visit LG's Web site. Clue: Thin is what thin does, and this ad shows it off well.