busy lizzies don't object to a bit of shade as long as they are kept moist. some ferns would be happy too as many are found in woods. also consider Heuchera and heucherella.

Agree with Seaburngirl, and Pulmonarias are also happy in shade, particularly P. Blue Ensign.

Lobelia does well in shade - I mean both the upright and trailing versions sold as box bedding in late spring. She might get away with Fuchsia too, they do well in shade, but usually a bit of sun for an hour or two works best.

Polyanthus Primroses are one of the things that we use in the shade in the winter, here in the desert. Primula malacoides and Primula obconica also work well that way, but they may like a little bit more warmth.

If you go for Busy Lizzies try to find some that are guaranteed mildew resistant as the others tend to die off half way through the season.
Snap dragons (can't spell the Latin name).
Mimulus should be OK - like plenty of water so don't let them dry out.

But I always stick to begonias in my north facing border - so easy and minimum care and don't seem to mind what the weather does. Mimulus would make a good contrast, especially with the lobelia Bamboo suggested.

Oxalis does well in shade & there are some striking colours available. Fuchsias are always nice. Ferns could be good if there's a fair amount of space: the Japanese painted fern 'Silver Falls' is stunning but deciduous.
For overhanging the edges Golden Creeping Jenny 'Aurea' has nice leaves year round.
Night scented stock seed can be bought for pennies & even if moderately successful would be nice near an open window.
Phew, scrolling through all those online retailers & making wish lists can be useful☺

Just stumbled across a Gardeners World article on just this subject- 'Four Container Ideas for Shade'.
Nice to have pictures of the plants together