I use Pregnancy+ and really like it. It's free for the first 12 weeks and then you have to pay a small fee for the full version.
It had a fruit size guide, daily blogs with useful information, a weekly blog to tell you about your babies progress this week. You can store belly pictures in there, it has lots of shopping lists of things you need to get before baby is born, an appointments reminder, lots of 2D and 3D images of what your baby may look like each week, name ideas...plus more useful stuff.