Most of the time, with other herbs, you can pinch off the flowers. From perennial herbs like chives, marjoram, mint, oregano, sage, tarragon and thyme; cut the plants back a bit give them a good watering and let them regrow. With that care, they will keep growing and produce more flavor-filled herb leaves for you to harvest. Use the pinched off flowers to spice up your meals in the mean time.
Basil can be halted by slipping off the flowers, but most of the other annuals need to be harvested or used before they start making seed, when it gets hot, keep an eye on them.