One of the most interesting things to me about this is the listing of gems/plugins and APIs used for each entry. If it's all in a structured form, it'd be interesting to see a table/list of the most used.

In terms of API, just browsing through, I saw that the Solo winner (http://medpass.es) used a government drug pill identification API I'd never heard of before:

http://pillbox.nlm.nih.gov/index.html