Earn more signup bonuses via business credit cards

Even if you don't own a business, you can sign up for business credit cards and earn more signup bonuses.  For example, the Starwood Preferred Guest American Express card is available in two flavors: personal and business.  You can sign up for both and earn sign-up bonuses for each of them.  When signing up for business cards, simply use your own name for the Company Name and leave the Federal Tax ID blank.