Running a close second to the Hollywood baby boom is the must-have-dog trend. Some celebrities, like Britney Spears and Tori Spelling, do the dog-baby thing in tandem. But others -- such as Jessica Biel, Rihanna, Gisele Bündchen and Paris Hilton -- are sticking with just their pup companions for now. Come meet some stars and their pampered pooches here!