Zinnias, marigolds, and cosmos seed. At the end of the month, you can plant tomatoes and peppers for the fall (but good luck finding the plants ). You can still plant palms and other tropicals - just be sure to water well at planting and deeply once every 5 - 7 days.
Tomatoes (mine have quit setting fruit, but I have a few left to ripen), green beans, okra, and figs
Any dead wood in your trees. Continue to pinch back your poinsettias for lots of flowers next Winter. Trim your basil (and all herbs) so they keep growing well (put basil on top of your sliced garden tomatoes - Yummy!)
DON'T BAG IT
With our high temperatures, mow no more than a 1/3 of your grass' height and then let it be. If you mow weekly, the trimmed grass won't even be noticable on your lawn - and it will drop down to the base of the grass quickly adding nutrients to your lawn.
A nice layer of mulch will cool your plants roots and give your landscape a nice finished look. Keep it a couple of inches away from your tree trunks.
Doug Welch's Texas Gardening Almanac It is a wealth of information!
It's getting too hot to work much later than 10 a.m. so sit back and enjoy the fruits of your labor.