This topic is probably why I joined this forum.
For the past few years I have had great success in my back yard garden (urban) with sunflowers that grow over 8 feet tall. They sort of work as giant radar dishes tracking the sun and are a magnet for honey bees, bumble bees, sweat bees, parasitic wasps, some sort of spider that has the same colors of the sunflower that captures flies without a web... I grow the sunflowers because they are easy to grow and they pop up over the fence like billboard advertisements for bees that may be foraging a few houses away.
One of the other flowers in my garden that attracts bees when it bolts (actually an herb like Borage.) Basil. The bees go nuts over the basil, I'm not sure if this would make honey taste like a light sweet pesto, but if you planted a row of basil, I feel certain that you would have a swarm of bees in your yard.
One of the plants that comes up in my yard without seed is a mildly invasive vine called the Passion Flower/Passion fruit vine. This has been a plant that all the bees in my yard flock to. at times, the honey bees will focus on one flower (the flowers are a tad larger than a silver dollar) It is easy to find 5-6 honey bees on one flower along with a couple of bumble bees.
http://en.wikipedia.org/wiki/Passiflora_incarnata
Along with these plants I have a large variety of other botanicals around the house that attract pollinators. Bee Balm, white sage, wild onions (That were imported into my yard by birds. various varieties of honeysuckle, zone 6a ice plant (That somehow survives winter freezing.)
I have some clumps of sweet peas, but I never see many bees get too excited over this flower.
Out of all the flowers I have summed it up to three in my garden (Sunflowers, Passion flowers, and basil.)
I am going to order some unusual heirloom varieties of giant sunflowers for next year, and Borage will grow next to my tomato plants as usual... Anyway, I am hoping that there are some other flowers that I can try out for next year that are just as impressive as bee magnets as what I have already have. I don't do bee keeping, but I am interested in bringing as many bees and pollinators to my garden as possible.