Some ideas:
bush beans
soy beans (produce very rapidly)
turnips

George
Tahlequah, OK

I would think squash.

Judson,

What you might decide to put there would vary depending on when your determinates slow down production enough that you decide to yank them out.

Although Determinates are generally described as 'producing their entire crop at once', I have not found that to be a hard-and-fast rule, especially with some of the newer hybrids. Some of the determinate varieties I grow put out successive flushes of flowers and fruit and produce all season long, from approx. May through November. I'm already harvesting ripe tomatoes from Better Bush (transplanted into containers in late February) and they'll produce at least 3 or 4 major flushes of fruit over the next few months. So, you may be surprised to see that as long as you keep your determinates well-watered, well-fed and relatively disease-free and pest-free, they'll produce over a fairly long period of time. Most determinates will put out a big first crop, and then succeeding crops will vary greatly from variety to variety.

If your determinate tomatoes finish up in late June through early-July, you could replace them with fresh tomato plants for fall. Or, you could plant one of the okras with a faster DTM, small to medium-sized pumpkins (Seminole can take the heat and is pest-resistant), black-eye or purplehull pinkeye peas, your choice of any kind of summer squash (crookneck, straightneck, pattypan, zucchini or a round 8-ball type), or bush lima beans. Bush green beans might work if the summer heat is not too brutal. You really wouldn't get much harvest from them until the cooler temps arrived in Sept. though.

If your determinates finish up in mid-June through late-July, you could replace them with something that you can harvest in the fall, including carrots, turnips, Swiss chard, broccoli, cauliflower or brussels sprouts.

If your determinates finish up in August or September, you could plant almost any of the cool-season crops for a late fall harvest, including spinach, lettuce, kale, cabbage, etc. You also could plant garlic in September for harvest in late spring/early summer 2011.

Dawn

As strange as it sounds, I have put in a small plot of corn near the end of July (after pulling my tomatoes) and it did well.

My Celebrity tomatoes have always produced a little bit again late during the years I have left them there and took care of them.