Flowers and plants that attract bees

With the Colony Collapse Disorder affecting the bee population, it's a good idea to plant flowers that attract pollinators to improve the success of crops and increase the local bee and butterfly population.
Common flowers that are attractive to pollinators are poppy, lupine, viola, wallflower, black-eyed Susan, Butterfly flower, Calendula, Dahlia, Amaranth, Marigold, Salvia, Sunflower, Zinnia, Portulaca, Lavender, Foxglove, Cosmos, Coneflower and Echinacea.
Anybody who has run barefoot in a yard knows that clover attracts bees. It is a great ground cover plant too.
Garden plants that are highly attractive to bees and butterflies include parsley, cilantro, thyme, dill, basil, chives, peas, squash and pumpkin.