I ould like to have a mini calendar webpart that gets that from the calendar list. Something like this sample calendar view
We had a similar requirement and discovered the following useful example for a custom display template using fullcalendar.js:
I personally found this quicker and easier to deploy than a custom app plus it integrates nicely with search for cross site collection queries.
Only issue I currently have is the 50 item limit for search results (raised a question here looking for a solution: http://sharepoint.stackexchange.com/questions/128879/sharepoint-cswp-50-item-limithttp://sharepoint.stackexchange.com/questions/128879/sharepoint-cswp-50-item-limit)