Is it lawful for companies to appropriate internship application materials for marketing purposes?

The "is this legal" question always sets me back a step.  When I think of something being 'not legal' or illegal, I think of activity that is criminal.  I don't know criminal law well enough to give an opinion, but if that is your question, it should be sent to the criminal law topic. I think I would term your question, "is this actionable?" The difference seems semantic, but the real difference is that if it were criminal, the state would pay to protect your rights, whereas if it is actionable, you will need to pay out of your own pocket to try to make yourself whole. I see two prospective actions when I read your question.  The first is in copyrights. Any work you create is copyright protected at the moment of its creation. If they posted your presentation without your permission, they digitally copied your work and that may be actionable. If you file for copyright protection within 3 months of creation/publication of the work, you can collect statutory damages and attorney fees for a copyright violation. If you file for registration outside that 3 month window, you can still sue, but you can only collect for actual damages (their profits, your lost profits, etc.). The second prospective action is misappropriation. Misappropriation is a state tort, but wikipedia gives a fair explanation of it. If you successfully brought an action, you could sue for your lost profits or their profits (not sure either would make an action worthwhile). And here is where we differentiate actionable and action-worthy. If you need to spend $50,000 to collect $1,000 (completely hypothetical numbers), while ruffling feathers in an industry where you are still trying to break in, this alleged misappropriation may be actionable without being action-worthy. Last, keep in mind that a determination of copyright infringement or misappropriation would require a review of more facts than you were able to fit into the question. The above is not analysis of your situation, but simply an idea of where I would start the analysis.