A stackoverflow for medicine could have enormous benefits, but considering how much "blind leading the blind" goes on there I'd be terrified if this is applied to a field with immediate consequences to people's well-being.

A stackoverflow for researchers in biotech/medicine/biology would be extremely useful. In biological research, if someone wants to do an experiment that they are not experienced in, they can review peer-reviewed published materials, but many important details are left out. There are many matters of technique, and many decisions about which protocol/solution/tool/etc to use for the experiment that may not be easily accessible via published sources. In these situations, a well-connected biological researcher would ask a colleague who is experienced in the particular experiment. This is not always so easy though, and much time can be wasted re-discovering a simple issue that many others already knew.

In software, this kind of knowledge has been available online for years. In other technology fields, this is not the case. A easy-to-use, well designed forum like stackoverflow for biology research could be a real boon for the field. The only problem I see is getting people to use it.

SO for medicine would be super interesting. If done correctly, it could be a really useful resource for physicians/biologists/etc.