An interesting way to get around the problem of people lying would be to aggregate all the search words a single person searchs and see if there are interesting correlations to other singular points. You could write a plug in that feeds all your searches annonymously to a central database where you could run a gamut of tests.

To your example, when I get a new drug I look up all the side effects (so I would look up thalidomide). Then I have a child and it turns out that my child has birth defects. I would look that up to see who else has that out there has experienced having a child with the same birth defects. As search continues, it would eventually pop up that people who look up side effects of thalidomide also look up birth defects. Then someone could do a serious study on it sooner than later.

As in all cases using data, the major impediment is anonimity and scale of data collection.