The amazingly comprehensive and free "About Herbs" app, developed by Memorial Sloan Kettering Cancer Center, helps both consumers and professionals decipher the benefits and risks of thousands of "botanicals, supplements, complementary therapies and more." Search a substance or a symptom — it's hard to find something they haven't included. Find familiar herbs like arnica ("a few clinical trials suggest topical arnica is helpful for osteoarthritis and significantly reduces bruising compared with a a placebo...") and more recent fads like yerba mate ("Regular use of mate is linked to increased risk of developing prostate, lung, bladder, esophageal and head and neck cancers.")
There are also featured topics, such as acupuncture or electromagnetic field therapy. Advice for consumers is relatively easy to understand, and includes potential benefits, as well as interactions and caveats, but unfortunately not much about dosing. Switch to the "professionals" mode for a more extensive scientific report.