I have a pretty insane summer coming up - I applied for/pursued a couple different opportunities, and they all ended up working out. So now I have no free time...whoops. First I'm spending a week at Cornell & Plum Island foreign animal disease center as part of USDA's Smith-Kilborne program (google it for more details). Then I'm doing a 6 week research project in Mongolia with a Swiss public health research institute (I just randomly emailed a researcher to ask about working with them, and surprisingly it all worked out). Oh and I applied for funding through my school so I'm getting an NIH grant which will cover all of my expenses. Then, in August, I'm doing an 8 day spay/neuter clinic in North Dakota with HSVMA/RAVS.
I didn't do anything last summer (I actually had to have surgery instead and spent the summer recovering), but definitely am excited for everything coming up this summer. And since I have a particular interest in public health, I feel like I'm getting training this summer that's going to be relevant to my career...which I won't get from the normal vet school curriculum.
So, in summary, summers are what you make of them. But if you also take a summer off...that's fine too.