This is apparantly called "Sea Breeze Fleabane"; not the most appealing name really, but so far it's doing really well, and claims to attract butterflies.
This is Agastache or "mosquito plant", also loved by butterflies and bees. It doesn't look like much, but it smells really sweet, and promises to have flowers by the end of the summer.
This one has the best name of the bunch (Firewitch?!!) and the best price ($2.50 on clearance). I'm thinking about getting another one. Basically all pinks and daisies should help attract The Elusive Three.
This one has seen the most action so far. It's actually called a "Butterfly Blue Pincushion Flower". I've seen bees around this pretty much every day since I bought it! It's supposed to be good for butterflies, and it's supposed to be a perennial- but I've managed to go through two of them so far. They don't winter over very well. I think it was like $3.33 at Lowe's a few weeks ago.
Plants to attract bees:
Plants to attract butterflies:
Pretty much anything else that attracts hummingbirds or bees!
Some tips to attract The Elusive Three to your garden:
Plant a variety of colors: Bees can see a wide range of colors, and will use this to seek out pollen.
They especially like: blue, violet, white, purple, and yellow
Plant flowers in clumps: Similar flowers planted together will make a stronger impression.
Don't use pesticides: These kill good creatures, along with the bad.
Use native plants if possible: Research shows that bees prefer native plants to exotic ones, about 4:1.
Give some shelter and water: Butterflies need places to rest and warm up, and all three of them need to drink! Having a birdbath, and some shadier plants will help all of these creatures want to be in your garden.