For more traditional machine learning research, there are common sets of data (i.e. MNIST for handwriting recognition) which serve to benchmark new algorithms.
The main problem with biomedical data is the difficulty of acquisition, and the fact that many researchers are afraid of discovering findings that they may have missed.
The hard part is getting the privacy right.
http://spluch.blogspot.com/2007/09/face-scan-can-spot-geneti...
and this one:
http://web.mit.edu/newsoffice/2012/amplifying-invisible-vide...
The first link dates back almost 5 years, anybody know what happened in that field?
1. http://archive.ics.uci.edu/ml/datasets/Parkinsons Does it really take 5 years for research to go mainstream? Max Little's original research on this was published in 2007. I think if I were able to better diagnose Parkinson's I would want to get it out to the public as soon as possible.
2. Why the need for clinical testing? It's not like it's a drug. Last time I checked a voice recording wasn't something that had too many side effects.