Google

Really, really smart people. Great pay. Great perks. Great culture. You can really tell that almost everyone there thinks they are doing what is best for the world. They aren't just there to make a quick buck.

It seems like there are a lot of people who are over-qualified for what they're doing. This isn't really an issue for an intern, but it could be down the road. As an intern, it can be stressful trying to get your project done in such a short amount of time. No one puts pressure on you, but if you want to get a full-time offer, you probably want to try to impress them.

Also, since they're obsessed with (un-biased) data, they insist on having interns do more interviews at the end of their internship if they want to convert to full-time. If you happen to have a bad day or get an interviewer you really don't click with, you're basically screwed, no matter how good your reviews from your manager and co-workers are.

After this, they are VERY strict about you not re-applying for at least a year, by which point anyone would have already found another job.