You can also create visual interest with strategically placed buttons or pendants. You can get bras that will fake cleavage or compliment what you have. I prefer the latter, though faking cleavage isn't so bad as long as you don't have to sustain it for long time and you don't take it too seriously. The sexier way to go is with bras that flatter smaller breasts. Try demi or sweetheart cut bras, and comfortable underwires.
Sometime spillage can be a good thing.
And these bras should be in fun, flattering colors and fabrics. Corsets, merry widows, Mary Janes and the like can also be entertaining when used properly. Also, check out the websites of various pharmaceutical companies for the latest product information and clinical research. Any search engine will give a complete list of companies. For reliable information on natural or herbal products, start with the Tufts University Nutrition Navigator.