I'm a web architect / software engineer at a language learning company.
I got the job by a referral of an acquaintance from a local software Meetup.com group that I attend regularly. When I got frustrated with my last job, I approached the leaders of the Meetup group (who I sort of knew as acquaintances by that point) and said "Hey guys, I'm sort of looking around now. Let me know if you hear anything." A few weeks later, one of those guys made an email introduction to me of another guy who works at the company I'm currently at. He brought me in for an interview... at first, I was just kind of going to the interview as a courtesy - I was pretty sure I didn't want to work here - but when I met the guys and the boss I would be working with, I was sold pretty quickly. They seemed like really fun, intelligent guys when we met and they are. If there was a point in the interview that sold it to me, it was probably the point where I asked them if we should start the whiteboard coding portion of the interview and they waived it off, saying "That's just for people who we think are bullshitting us. We can tell you know what you're talking about and what you're doing."
I just got back from the beach for a week, and while it was nice to be away for a little bit, I was genuinely excited to get back in the office on Monday. I don't remember ever feeling that way at any other job I've had, so I guess I have to say this is my "Dream Job". That doesn't mean I want to do it forever - I'm a firm believer that even the "Dreamiest" job doesn't beat working for yourself, but I have to say I really enjoy it. Unless someone offered me something on the order of 2-3x what I make here, I wouldn't consider leaving (and I make a pretty decent amount for my region/experience).
What makes it that way?
1. Boss. Best/most competent guy I've ever worked for. He somehow has the "magic touch" of keeping the team focused on things we can deliver, calling bullshit on all the paper-pushers and meeting-mongrels that try to sap our time ("No one on my team has a company phone. No one in this company has the right to innterupt my devs while they're working."), and rolling up his sleeves and coding when we have to stay super-late to get something done (only happened once). He also judges on "body of work" more than individual incidents ("You went out at 2PM and get drunk with your co-workers yesterday? No problem, you usually get your shit done in good order and on time. You showboated about staying until 1AM last night? Bullshit - on a regular basis, you don't get shit done. Try harder.")
2. Open-ness of the team. "You have been messing around with a new library/framework at home for the last couple of weeks and you really like it? Come in and show it to the rest of the team for a couple hours tomorrow. Team discusses it, weighs benefits/drawback/long-term-maintainability...it's in production a week later." "You met an awesome guy at a meetup last week? Bring him in here and interview him. Two weeks later, he's hired."
3. "Goldilocks" company atmosphere. Not "douchy-SV-startup concrete walls and beanbag-chairs", but not "corporate cubicle farm" either. It's a great mix of people from different parts of the world, different age ranges / genders / etc. We have free sodas/coffee, but not free beer. People leave at 6. There is usually a happy hour every couple of weeks where we get together at a crappy bar and have a great time, but no one's social circle consists entirely of coworkers. If you're married/kids people tell you what happened at the happy hour the next day so no one feels like they're "left out".