I've been kicking around Ruby and the rails framework and have been considering recommending to a client-of-a-client that they use it to rebuild their site, which is currently built in very bad ASP classic that will have to be rewritten from the ground up regardless of what technology is used.
One thing I'm missing from my pitch is a list of major sites using Ruby-on-Rails. Are there any yet?
Twitter, although it's been said that they're abandoning that framework (as it turns out that RoR is hard to scale). If you're building a website that gets heavy traffic you may want to check out some of the interviews/articles related to the problems they've been having (as it might help you in development :):
http://www.radicalbehavior.com/5-question-interview-with-twitter-developer-alex-payne/
http://www.techcrunch.com/2008/05/01/twitter-said-to-be-abandoning-ruby-on-rails/
http://www.texasstartupblog.com/2007/04/12/twitter-blaming-ruby-on-rails-for-failures/
http://www.slideshare.net/Blaine/scaling-twitter
More sites:
Basecamp
43 things
pitchfork media
penny arcade
a list apart
the yellow pages
There are some big sites listed here: http://www.mslater.com/2006/11/17/sites-built-with-ruby-on-rails
And you can view Ruby on Rails sites listed by traffic here: http://rankedindex.com/rails
There's twitter (with problems) and basecamp and a few others, but it'll take time. PHP was probably 5 years old before yahoo became the first really large website to use it.
There's also a tradeoff involved: most of these languages and frameworks are great to develop in. Once traffic and revenue rolls in, it becomes cheaper to rework at least parts in C++ etc.
I hope to be in production in about two weeks. My application will be used by insurance companies to authorize charges for patients in a hospital.
http://successbox.co.uk - elearning, modular premium courses made up of downloadable and branded PDF/MP3/MPEG files.
http://kickstartme.co.uk - event management system for web developer courses
These are deployed on to production servers using Vlad, mod_rails and Apache.
The company I recently left, and now contract with are switching to rails from asp.net on the belief that it will improve development. They are scrapping 6 months of develoment, and so I'll be interested to see what comes of it.
Obie Fernandez has a list here: http://blog.obiefernandez.com/content/2008/03/big-name-compan.html
One from the Financial world: http://about.reuters.com/productinfo/compliance/MiFID/material/ReutersTCAS.pdf
Edit: In the interests of accuracy, I should mention that this app was discontinued on 31-Dec-2008 :)
yellowpages.com (mentioned above) is probably the largest site of any of these in terms of traffic and page views/sec. They've done a nice job.
Somewhat out of date list of the largest sites running Rails. http://rails100.pbwiki.com/Compete+Rankings
Don't buy into the Rails can't scale hullabaloo. If you are an ignorant twit, nothing scales. There is no platform out there that doesn't have the same bottlenecks as Rails, and guess what, it's mostly the database and disk. Caching and query optimization is your friend.
Rails100 lists Rails-powered sites and orders them by Alexa rank. At the top - scribd, hulu, yellowpages.com, urbandictionary. http://rails100.pbwiki.com/Alexa+Rankings
My site is currently in the middle of this list and I can say that most of our scaling and tuning effort has gone into the database and not Ruby/Rails.
The ranks are updated regularly (the sites themselves, slightly less regularly)
We've got a list on BuiltWith Trends as well -
http://trends.builtwith.com/framework/Ruby-on-Rails
Scribd appears to be the biggest user.
Parts of http://www.lonelyplanet.com are using JRuby on Rails (I'm a dev there). Rails is also used for serving up in app purchases for the iPhone app, plus a few in house apps.
The rest of the site is written using various J2EE tech. The Rails part of the site is much easier to work with and iterate through than the Java parts. And when it comes down to the DB and browser bandwidth usually being the bottleneck, there isn't much between them in terms of performance.
Twitter is not abandoing rails as everyone ponts out they simply moved their middleware layer(queue) to a more non scripted non dynamic language(scala) that will definately process and scale better than ruby.
Twitter still uses rails extensively for their front end which they keep updating in small iterations.