This question comes up often, the answer should probably be in the FAQ. Here are some links with lists of YC funded companies:

* An old version of the Wikipedia entry contained a list of YC funded companies. It was removed. It should probably be setup as a separate article (that would require finding some HNers who have some of the elusive wikipedia-power):

http://en.wikipedia.org/w/index.php?title=Y_Combinator&o...

* CrunchBase lists some of the investments on the YC page. It would be a good idea for those who have been funded to add themselves to this list and to fill their profiles in:

http://www.crunchbase.com/company/y-combinator

* There used to be a list on the about page, which you can see if you go to the Wayback Machine on archive.org:

http://web.archive.org/web/*/http://ycombinator.com/faq.html

for eg.

http://web.archive.org/web/20070116090613/http://www.ycombin...

http://web.archive.org/web/20080415144853/http://ycombinator...

* This blog post contains a list plus stats, up to '09. He used the archive.org pages to extract a list of companies from each class:

http://blog.awesomezombie.com/2009/12/analyzing-y-combinator...

* This spreadsheet seems to be the most exhaustive list, and it also contains Techstars, fbFund etc.

https://spreadsheets1.google.com/ccc?key=t_toYuVyy6fci0MAiIa...

Don't know how current this is, nor how accurate but I've seen it posted around here a few times.

https://spreadsheets.google.com/ccc?key=0AkkhSN3vaY4jdF90b1l...

Yes, that's the list for the Y Combinator startups. Does anyone have a similar thing for those coming from or first posted on hackernews? I guess this would be all those weekend projects and "Please Rate My App" posts.

for yc funded startups: http://yclist.com/

It would be interesting to know what programming language(s) each of these were written in.

Thanks, all comments were helpful.