As first years, we're all going through this now! It doesn't seem like there's a typical summer- I have friends who are getting married and taking the summer off, some that are working through school programs and staying in Worcester, and some heading abroad via funding for most of the summer. That does seem to be a popular choice, as it's pretty easy to get funded to work/language study abroad (Especially through the Multicultural Pathway, which you guys will hear about, but really anyone can get funding!)
As for paid research, etc: Aside from finding research projects on your own (which is very do-able, with lots of funding opportunities), there are 2 main programs that students apply through. One is a service-learning program, which includes placements working in different agencies or clinics, or things of that nature. It's shorter but not really research-based, though projects can come out of it. The other is for research- anything from clinical to bench, with a published list of available projects. Both of these are funded! It seems that everyone who is interested in a project/program will get funded, but I don't know for sure.
From talking to second years, it seems like anything or nothing is a good option! Traveling, working, research, or lounging around. But there are plenty of opportunities!
P.S. COME TO SECOND LOOK!