Homeopathy works on animals as well - placebo effect for sure.
I am fairly sure that acupuncture has been shown in some double blind studies to have an effect.
NICE is suggesting it is useful in chronic back pain. Googling finds a fair few studies that show effects. I haven't looked closely at theses studies and I would say a healthy sceptisim is needed.
"Conclusions. This study showed that active acupuncture was more effective than sham acupuncture in decreasing the symptom scores for persistent allergic rhinitis and increasing the symptom-free days. No serious adverse effect was identified. A large-scale study is required to confirm the safety of acupuncture for children."
http://pediatrics.aappublications.org/cgi/content/full/114/5/1242
and one that shows no effect
However reading around the best conclusion I can draw is that its worthy of more investigation but the studies are done so far are often poorly constructed and not rigourous.
analysis of a cochrane review which concluded ( the cochrane review) Overall, the existing evidence supports the value of acupuncture for the treatment of idiopathic headaches. However, the quality and amount of evidence are not fully convincing. There is an urgent need for well-planned, large-scale studies to assess the effectiveness and cost-effectiveness of acupuncture under real-life conditions.'