Over the past few years, my favourite container plant - by far - has been Supertunia 'Pretty Much Picasso' from Proven Winners (top photo).. the large flowers are an intense purple-pink edged in glowing lime green - stunning! They're also vigorous, densely flowered and perfect for pots, hanging baskets or window boxes.
Proven Winner also has some great new releases for 2011.. including Absolutely Amethyst™ Iberis (photo courtesy of Proven Winners). This hardy perennial (zone 4 to 9), also known as candytuft, has soft lavender flowers that carpet the ground in late spring. I love candytuft in a rock garden, but it also looks lovely in front of (or amongst!) spring flowering bulbs like tulips and daffodils or other early perennials. Don't forget to tuck a few plants into spring containers and then move them into the garden once the flowers have finished. They'll come back year after year after year..