Gardens Alive, a mail-order company, does still offer a pollinating spray for tomatoes. Generally, bees or insects do the job for you without need for a spray.
But if they don't, you can easily pollinate tomato blossoms by hand. It's not hard at all -- just tap the open blossoms gently but firmly with your index finger. It's best to do this two or three days in a row to be sure you hit the exact time when the blossom is completely open.
The main reason that tomato blossoms don't set fruit this time of year is that the daytime temperature is too high. Although there are a few tomato varieties that have been bred to set fruit at temperatures above 90 degrees F., most just drop off the plant without forming tomatoes until temperatures moderate.
I've read that high humidity can also cause blossom drop, but I lived in the South for years and never experienced it.