Given the effectiveness of acupuncture for nausea and vomiting (see here), it should come as no surprise that controlled studies have shown that acupuncture can significantly reduce motion sickness (Hu Stern & Koch 1992; Hu et al 1995).

Hu S, Stern R M, Koch K L 1992. Electrical acustimulation relieves vection-induced motion sickness. Gastroenterology 102(6):1854-1858.

Hu S, Stritzel R, Chandler A, Stern R M 1995 P6 acupressure reduces symptoms of vection-induced motion sickness. Aviation, Space, and Environmental Medicine 66:631-634.