Interesting article on how webpop built their infrastructure on Rackspace's cloud. Includes links to a few useful tools (chef, wormly, new relic, nagios, ganglia, and others).
Cloud hosting, bit pricey, can be configured ram / disk / cpu / etc. Works out twice as expensive as Linode. Arguably has a more "enterprise" featureset.
Handy article introducing chef and providing a few links. A little out of date now, but provides a useful intro.
Useful article on how to deploy django apps on nginx. Handy.
CDN plugin for Magento that supports Rackspace and Amazon AWS CloudFront. Pushes images on demand, claims to be simple to integrate, and is free.
Interesting article comparing Rackspace and AWS performance when applying high frequency trading strategies against 10 years of archive data. Rackspace io kicks ass, CPU slightly ahead.
Very simple guide to using ufw to create firewall rules. `ufw allow ssh/tcp && ufw allow http/tcp && ufw allow https/tcp && ufw enable && ufw status` done. :-)