I am still a traditional classroom teacher so my feedback is usually on paper on a rubric chart. I create rubric charts from http://rubistar.4teachers.org/index.php which are free and they can be customized to your specifications. In my Spanish class, we do a lot of presentations of cultures around the world. A project that I usually do is that I assign each student a country with a set of questions of things to research. The research then needs to be presented in a power point or prezi and then they need to present that to the class.
For presentations: I provide feedback on presentation of the subject, the presentation material, grammar and appearance.