BHA's Goat Milk and Honey shampoo bar has a mild, earthy scent with this blend of essential oils that are great for your hair:  peppermint, cedarwood, amyris, thyme, rosemary, and tea tree oil.  (All of the essential oils I use are 100% theraputic grade.)  I made this because I noticed my hair has been thinning out, and wanted to try out these oils in a shampoo bar.  I will update on how I think it's worked (it just finished curing, so I just started using it).
Essential oils used in this blend are said to have these benefits for hair:
peppermint: promote hair growth
cedarwood: antifungal, regenerate hair, treat hair loss
amyris: antioxidant, antiseptic, natural emollient
thyme: promote hair growth
rosemary: improves cellular generation, therefore improving hair thickness/growth
tea tree: antibacterial, antimicrobal porperties, helps unplug hair follicles and increase hair growth, also used to treat dandruff