the top of my list is Strongylodon macrobotrys...The Jade Vine.

A friend of mine has hers in flower at the moment and I could just stand and stare at it all day

Great choice Sarah. This would certianly have to be high on the list.

For those readers who don't know what this plant is here's a pic

Kingsbrae Garden in St. Andrews, New Brunswick (Canada) got the first Wollemi pine in the country a year ago, and I saw it this summer. It's a really interesting plant, very attractive and has settled nicely--though Kingsbrae has it in a huge container (which is inside a large, wrought iron and locked cage!) for a few years until they decide whether it can handle being out doors yearround.
I've only seen photos of these others, but they're all quite remarkable. Funny how so many of them smell of rotting meat so as to attract pollinators.
Fascinating post, Stuart, both this one linking to the Divine Caroline one and your own top 5 plu 5!

Thanks for your comment jodi. It's interesting that the world is still wooing the Wollemi as here they are fast becoming the next trendy must-have. Every gardener seems to be finding a spot for one in their garden regardless of whether it suits or not. Still, if it wasn't the Wollemi we'd be fussing over dwarf agapanthus or weeping maples.