Sunpoint Products Inc., in Lawrence, Mass., a maker of cleaning products, has been using every bit of packaging real estate to establish and extend its brand. Sunpoint CEO Brooks O'Kane covers the back of his bottle labels with interactive screeds. One suggests that customers pop by the company's HQ for Ping-Pong. Another shows an embarrassing picture of O'Kane's childhood friend and prompts customers to send E-mail to the poor fellow to tease him. He says the ploy bemuses customers and differentiates him from the corporate types he competes with.