i've always loved these teeny tiny blue flowers. i wish i knew what they're called! they're even smaller than forget-me-nots. or smaller than the variety that people grow in their gardens, anyway. these just grow in the wild, you find them in lawns sometimes. i guess the fact that some have settled on the balcony is a good start, though.
EDIT: they are field forget-me-nots! the ones grown in gardens are woodland forget-me-nots. that explains that. the flowers do have exactly the same colour.