M.
Yes, Zoo School is fabulous for the animal lovers. I'm not sure if they will let him take his camera, but they go into the zoo to see the animal they are studying every week, unless it is lightning. They also have a pick-up/drop-off line, which is nice.
Another great one is Van Grow for kids, it's on 7th St, west of downtown. It's a great art studio and they do different projects each week - they encourage individuality, so all of the art work you see will be different.
The other idea I would have for you is a physical activity. Some might think karate is too much, but a great school makes a big difference. My son started at 4 and has had a great time and learned so much. Our school doesn't allow fighting or sparring at this young age. I would drop in and watch classes at a few places before you sign up. Some t-ball leagues have fall and spring teams, so he could play from Sept-Oct and again from Mar-May. Also fun.
Get a copy of July's Fort Worth Child - it has tons of activities in it with all the phone numbers. It's a good resource.