How Ravelry Scales to 10 Million Requests Using Rails | High Scalability

Statistics
# 10 million requests a day hit Rails (AJAX + RSS + API)
# 3.6 million pageviews per day
# 430,000 registered users. 70,000 active each day. 900 new sign ups per day.
# 2.3 million knitting/crochet projects, 50,000 new forum posts each day, 19 million forum posts, 13 million private messages, 8 million photos (the majority are hosted by Flickr).
# Started on a small VPS and demand exploded from the start.
# Monetization: advertisers + merchandise store + pattern sales
#
Platform
# Percona build of MySQL
# Capistrano for deployment.
# Nginx is much faster and less memory hungry than Apache.
# Xen for virtualization
# HAproxy for load balancing.
# Munin for monitoring.
# Tokyo Cabinet/Tyrant for large object caching
# Nagios for alerts
# HopToad for exception notifications.
# NewRelic for tuning
# Syslog-ng for log aggregation
# S3 for storage
# Cloudfront as a CDN
# Sphinx for the search engine
# Memcached for small object caching
(Link: How Ravelry Scales to 10 Million Requests Using Rails | High Scalability)