Google scholar.

Lovely new interface for research searches.

Forget medline, forget all the multitudes of different databases out there, google has just launched a search engine for scientific research. Without ads. Here: http://scholar.google.com/.

Sure, you have to know the latin names, but it's still very very cool, no?

Hypericum: 4480 results
St. John's wort: 606 results
hypericum + medicine: 1230 results

Filipendula: 927 results
meadowsweet: 194 results
filipendula + pharmacy: 20 results