A number of supplements tout their benefits for improving mood. I can vouch for one. Folic acid, or Vitamin B12, has significantly improved my mood on the days I take it. I take about 1600 mcg (4 400 mcg pills) and feel at peace and exuberant all day long. I also take effexor, which folic acid has been shown helps the body to absorb better. I wouldn't take folic acid every day though. Over time it seems to build up, and you start getting cranky and irritable. So only take it every few days, or only on days you feel really down. Here's a rundown on some other popular suplements used to treat depression. As usual, consult your doctor on this.
http://www.cnn.com/2010/HEALTH/06/11/sup...epression/
http://www.cnn.com/2010/HEALTH/06/11/sup...epression/