I didn't realize it at the time, as it was my first time going through the interview/offer dance, but having much more experience with these things now (from both sides of the process), I can honestly say it ranks as the best I've ever heard of.
a) The technical portion of the interview was the best I've ever been through. It culminated in them asking me to set aside 4 hours to come into their office and work alongside them (asking questions if I needed to), writing an HTTP server in C.
I almost shat my pants when I heard the question, but to this day its the most rewarding technical interview of my life. I started off with a problem I wasn't sure I could sove in the allotted time, I _built_ something, and it _worked_. (Well, it mostly worked. There was one elusive bug I couldn't figure out that day. I had to leave because of another commitment, but I promised to come back the next day and fix it. When I got back the next day, a senior Meebo engineer had spent 3 hours debugging my code until he figured out the problem. We code reviewed my code line-by-line as a wrap-up to the interview.)
b) The non-technical portion of the interview was the best I've ever been through. They were very concerned about the ever-elusive "culture fit", and the entire team made an effort to get to know me, taking me out to meals, etc. I met all three of the co-founders (Seth, Elaine, and Sandy), all of whom I'm sure were busy trying to build a product and grow a company, but they were incredibly warm, genuinely interested in getting to know me, and generous with their time.
c) They gave me a great offer. For a fresh-out-of-college student with not much real work experience, both the salary and the equity portions of my offer were extremely generous. I didn't even have to negotiate. At the time, Seth explained they didn't want to go through a contentious negotiation process, so they were opening off with a generous offer and it wasn't really open to negotiation. It was, indeed, a generous offer. (Five years of experience later, and I'm making less money, adjusted for inflation, than Meebo offered me as a fresh-out-of-school untried new hire.)
d) The post-offer process was the best I've been through. At the time, I knew nothing about startups, stock options, VC, etc. I didn't even know how much I didn't know. At his own initiative, Seth (the CEO!), took the time to explain the equity portion of my offer. The offer included a number of options and a strike price (standard), but unprompted told me about the other numbers I should be concerned with: total shares outstanding, fully diluted % stake, preference multiples, etc. There's much more transparency about this stuff today (blogs, etc), but at the time no one else explained this stuff to you (and as a stupid college student, you wouldn't know to ask). Even today, in a much more competitive hiring environment, I hear about companies that tell experienced engineers (who know what they're negotiating) that certain numbers which are essential to understanding an equity offer (like total number of shares outstanding) are "confidential".
I ended up turning down the offer, but I have enormous admiration and respect for Seth, Sandy, Elaine, and the whole team at Meebo. Congratulations on your many successes over the years, and I hope to continue seeing great things from you in the future.
You live, you learn.