Floating Flower Tip - Most flowers float pretty well on their own until they start to pool with water and slowly sink. For a longer lasting centerpiece, use bubble wrap to make little skirts for your flowers.
Indoor Tulips - Fill glass container about with glass marbles or decorative rocks. Set tulip bulb on top of marbles or stones; pointed end up, add more marbles or rocks; so bulb is surrounded but not covered. Pour fresh water into the container.
Give framed images a striking effect by hanging them above and below an invisible line. To unify the group, choose a single color for all frames and, if displaying photographs, stick with either all black-and-white or all color shots.