Don't do it.
I just studied abroad and spent a lot of time on a research project that was amazing, but that I realize now could probably have been done at my home university. I feel like I missed out on the things that you learn from studying abroad - this is cliche, forgive me - the types of things you learn about yourself. Go out and experience a different life, rather than clinging to what you have in the US. Your character will grow and change, which is so, so important, even if you can't put it on your MD application.
Furthermore, things to consider (some already mentioned):
- near-impossible to volunteer in Europe if you're not completing an organized clinical
- from my experiences, they have very few volunteers here, and most have specific medical skills (ie: do you have anything special to offer them?)
- if you don't speak the language (fluently, not the "dutch in 60 minutes" sort of thing), you will be more a burden than an asset
- most countries' student visa requirements ban all types of non-academic work, so read the fine print carefully
- you'll find once you're here that there are so many more things you want to do than you anticipated. don't over-commit yourself to the types of things you'd do in the US. that was my mistake.
good luck!