Seen as its so hot you don't want to wear long sleeves, yet you still want to wear something with a collar? Well the blouses below with no sleeves but collar seem perfect, I've seen a few people out and about with this kind of thing going on.
The Peter Pan Collar Tunic, £28 from Topshop, is my favourite with it's soft round collar. For those who like their collars pointed, American Apparell have a sleeveless shirt in a really great selection of colours (as always!) with a mesh feel to it. I would personally style the pink one with a flirty skirt, perhaps in light blue or gingham, and for a harder look, the black one witha leather mini skirt and heart print tights.