Well, for growing in the ground assume your 6b but you could mulch up around 7a hardy plants to get them to survive, or even bury some 8a plants. I turn my Heimias into pyramids of leaves and sticks to survive my 7a winters and its about time for me to dig up my turmeric, stick them in a pot, and bury the pot for the winter.
Peganum harmala would survive if the winter isnt too wet. Their 'love' of dry soil is vastly exaggerated in the summer but I wouldnt trust them to a wet winter.
Desmanthus leptolobus should survive without mulch and easily would with mulch. Desmanthus illinoensis certainly would survive.
Silene capensis may survive, I'd mulch it there until certain. It survives my dry 7a winters without mulch.
Daturas would, as theyre annual, but most would only grow them as ornamentals.
Morning glories can be grown as annuals.
For containers, that removes zone consideration and shifts more emphasis to things like humidity. Like in my extremely dry environment I could never grow stuff like kava and iboga.
Cacti are great for bringing indoors because you can make them go dormant. Many of my cacti I grow in the ground or pots outdoors spring through summer then get them dormant and bring them inside and store them in a cool room with the ones that were in the ground packed into small crates.
One trick for pots is to plant the whole damn pot in the garden, roots will grow out the drain holes, then in fall prune down the top growth and sever the roots coming out the holes and bring the thing inside for winter. You could make some gnarly jumbo bonsai that way.
Some of the changa admixture plants could grow in zone 6b. Mullein, catnip, Salvia splendens (grown as an annual), etc.
People who drink alcohol sometimes grow Primula veris to increase alcohols potency. Its a perennial hardy to zone 4 or 5.
Salvia sclarea is hardy to zone 5 and it has the same effect, but is bitter so its used in brewing beer in place of hops.
Oh, and hops is hardy to zone 5 as well.