Reddit. I remember when PG posted on comp.lang.lisp about this startup that he'd funded that was using Lisp. Checked it out, thought it was lame, because it was just a bunch of links with voting arrows, and the links all seemed to be submitted by the founders, spez's girlfriend, and PG. Came back a couple months later when they added comments, and stayed ever since.

HN. I joined the day after it opened for public use (it had been in beta for YC founders for about 6 months previous).

FictionAlley.org. I started lurking when they had a couple hundred members, and joined as user 1881. Joined the staff a couple months later, when we were at around 2500 registered users, and when I left the staff 3 years later, we had over 100,000.

Dropbox. Like you, I remember being super impressed by Drew's little demo on the HN forums. I actually had lunch with Drew, Arash, and Aston right after they got their Sequoia funding to discuss joining the company as employee #2. Had my own startup at the time and wouldn't leave my cofounder; I keep wondering if this'll be one of those decisions I'll regret forever, but OTOH the failure of my startup afterwards led me to Google, and that's been a pretty good experience too.

FaceBook. In September of 2004, a couple of my friends were all excited about this new social network that had just expanded to Amherst from the Ivy League. The founders had apparently just moved out to Silicon Valley, gotten some angel funding, and were shopping the company around to acquirers and VCs. I joined, found it kinda "meh", but friended all my friends (and a few people I met just once or twice at parties). At the time, they had profile photos, contact info, and the Wall, but nothing else. No private messaging, no chat, no photo-sharing, no apps, no events, no groups, etc.

Avici (remember them? They sold the massive routers that Enron Broadband and many of the major ISPs of the first dot-com boom used). Sometime in the summer of 1995 or 1996, we were sitting by the pool with the family of one of my friends from middle school, and talking computers. My friend's father said he and a bunch of his coworkers from BBN were founding a new company. They'd wanted to do these multi-terabit/second routers for years, and given how the Internet was exploding, it was now or never. They IPO'd at a market value of over a billion dollars in 2000, my friend's dad cashed out as soon as the lockup was over, and then the company promptly tanked.

Akamai. I was in a support group for gifted & talented kids with Reid Barton, the 4-time IMO gold medalist, when I was a teenager. Sometime around 1998, my dad was talking with his mom about what he was up to. He'd been working on the Cilk programming language at MIT, and one of the professors in the department was leaving to found this Akamai startup. Reid was going to join him as an intern. The irony is that I waited until the dot-com bust, after Danny Lewin was killed on 9/11, then picked up a whole bunch of Akamai shares on the open market at a price lower than the strike prices of virtually all the employees. That pretty much funded my first startup.

Facebook probably the biggest example. I remember when it was Harvard and MIT and actually just for college students. although I used it everyday, I did not at all foresee its skyrocket. now any service I visit every day I pretty much assume will go big. well HN maybe not...

I remember something called the "Game Neverending" shutting down because its developers, while working on an updated version, accidentally created a photo sharing website instead.

HNers of the right age have probably been witness to every big startup in the last decade. I would be more interested in hearing what effects the big startups have had each person's own projects.

Tumblr. I remember first posts around my online social circle mentioning this easy, simple blogging platform, and lots of people including me started using it right away. I'm still a big fan and use it in lots of different ways.

Posterous. Here the first thoughts were different and it didn't kick in among most of my friends. I used it for some time as an experiment and got to know it quite well, but somehow I didn't enjoy it too much, now I know I'll be using this platform for some projects soon.

Flickr. I wasn't much into photography back then, but my mates who were active photogs got crazy about it. At first I really didn't like it, partly because of the early UI/UX, partly because I wasn't really sure about the idea of hosting pics 'out there' and didn't like the ToS. After a few years, when I got into photography as a hobby, started using it right away (exploring and sharing) and I do it actively to this day.

Youtube.

Lots of local companies, which are probably irrelevant to most of the HN crowd, but I'll mention some anyway: gadu-gadu (from a simple sms gate app to being THE instant messenger in Poland completely killing ICQ here), grono.net (first leading social network), nasza-klasa (classmates social network), wykop.pl (digg clone).

Gee. Every YC startup since the first batch, that was successful, that people paid attention to, was witnessed by those people paying attention to it, except possibly during the dark period when Reddit was in decline and HN was not yet around, so it was a bit harder to notice. Well that's a rather snide way to put it.

Then there are some non-YC things, like Mibbit, Tarsnap, and BCC, which aren't actually "big," but have gotten enough coverage here, and seem to have gained some permanence.

I probably could have gotten a nice Twitter username if I had bothered. Oh well.

I remember reading on TC a few years ago about a new P2P music sharing, micro-payments service (all the buzz words in). You would download a client and share your music collection on a P2P network and get paid for sharing (or something like that).

I don't know how big they are but they are quite well known: Grooveshark

Posterous.

I used it a few days after it was launched public and thought it was just anther blogging platform. I hardly paid much attention. After an year or two the service started to gain traction when some famous bloggers moved to Posterous.

I still don't use it but it certainly has grown big.

Heroku. I was member no. 601

FedEx