If you don't know Russellia equisetiformis already you've been missing out. I often describe this plant as hummingbird crack, since once they find it that won't leave it alone. It's not for every spot with that 3' tall and wide mop-like growth, but it is great for raised beds, hillsides and pots etc. It fills the large pot in the garden nicely. The foliage is reminiscent of horsetail hence the specific epithet, so it has a soft broom-like texture that can be used to good effect.
My experience is that Russellia is very tough and drought tolerant, but if you give it regular water and occasional feeding you can expect flowers all year round. The big display comes in late winter and early spring usually.
Anyway, if you don't have you one yet, get one.