The first time I looked for a sublease, no less in NYC, it felt like falling into an internet pit of inflated rents, stock photos, and poorly written descriptions.
I know it has the whole 'creep from Craigslist' and 'Craigslist killer' reputation...
...but I've actually found most of my apartments, or at least nearly half, through Craigslist. I've been completely satisfied with all of the apartments that I've subleased through Craigslist and have only had one unpleasant roommate experience (and even that wasn't a terrifying nightmare - just hard partiers who smoked pot in the apartment, got really trashed, and forgot when they drunk vomited all over the bathroom).
Craigslist also seems to always have a way of reminding me of how small the world really is - I have inquired about rooms being sublet by former classmates, peers from high school, RA's, and more!
I'm very hesitant to recommend this one, because I've never gotten a solid lead from the site and most often there's no response in reply to inquiries about listings. Still, if you need a room near a university and other sources are running shallow, there's no harm in taking a look at ULoop.
Just don't get your hopes up!
This one is best for medical students on rotation - unsurprisingly, because that's what it's intended for. If you're not doing a medical rotation but still need to be near a hospital for some reason, whether it's a job, contracted project, internship, or anything else, it's still worth checking out. It's not exclusively for medical students and you don't need university affiliation to view the listings.
How often do you sublease?