Don't forget to water. This is a critical time for ripening veggies so don't let them dry out if the rain slows down. Water deeply and thoroughly.
Keep harvesting. Get out into the garden every day if you can to keep everything picked clean at the peak of ripeness. Beans, peppers, tomatoes, zucchini, and so on will keep producing if you keep picking. Share extra with neighbors and loved ones, or preserve for the long winter ahead.
Plant some quick crops. All kinds of greens will pop up and be ready to eat before first frost if you plant them now. No open space left in the garden? Scatter the seeds under tall growing plants like corn and tomatoes. They'll appreciate the shade.
Annual Gardens and Containers
If it needs a haircut, give a haircut! There is still time for flowering annuals to recover from a haircut and bloom again before frost. Snip off spent flowers to encourage a re-bloom.
Repot your containers. Give those plants a fresh new home if possible, with new potting soil and a bigger container. If that's not possible, take the top 3 or 4 inches of potting soil from the container and replace with fresh stuff.
Begin prepping for winter beauty. Plenty of annuals will stay blooming an beautiful long into the winter if you bring them into the house before frost. Pot up a few geraniums, petunias, fuschias, nemesia, etc. in hanging baskets or containers, and remember to bring those containers in before frost.
Harvest herbs frequently to keep them producing like herbal factories. Dry the harvest completely and store in zip top bags for winter use, or freeze in ice cube trays.
Pot up a few good specimens for household plants. Rosemary will live happily through winter in the house, but not so happily under four feet of snow. Even tender annuals like parsley and basil make good houseplants, although don't be too disappointed if they give up the ghost in February.
Trees & Shrubs
Trim out the dead wood. Get down inside your shrubs and cut away dead sticks from the center. Blooming shrubs which are past their bloom benefit from a moderate haircut at this time of year, but don't go overboard.
Pick some apples. Keep an eye on your apple and other fruit trees. If the branches are bending under the weight of ripening fruit, pick some (even thought it's not ripe yet). The fruit that is left behind will finish larger and juicier, and no branches will break.
Plant new trees and shrubs now. It's the perfect time to plant these items- they have time to get their roots down before winter sets in.