An anti-acne body wash!
There's Murad's Acne Body Wash, the Peter Thomas Roth's Blemish Buffing Beads Body Wash, and Mirh's Body Bar (which isn't a body wash, but an exfoliating soap). It depends on you personal preferences; I find that exfoliating always helps to make my skin softer and clear up breakouts fasters, but depending on your skin type it may not respond to exfoliation that well.
Also, if you find that you get large white heads or skin abscesses (boils) on your back, it will help to spot treat those. My personal favorite spot treatment is actually by Clean and Clear, which also happens to be cheaper and sold at any drug store!
Good luck :-)