It turns out that cheezburger-crazed LOLcats were just the beginning. Now, the kitty stranglehold on the Web is spreading. The iPad is threatening the dominance of the scratching post as the most favored feline plaything and hangout. Tablet apps intended not just for cat owners, but for cats themselves, have been cropping up in disturbing amounts. We sifted through all the catnip to bring you the eight cat iPad apps most worth knowing about.