Not sure which aspects in particular you are referring to, but here's some of what we use:
Revision Control - Github.com
Market Research - Hoovers.com, LinkedIn.com
VPS hosting - Rackspace Cloud
Short-lived hosting for experimental shit - Amazon AWS
CRM: SugarCRM (self hosted)
Competitive Intelligence: FUCIT - Fogbeam Universal Competitive Intelligence Tool (internal tool)
Wiki: Mediawiki (self hosted)
Continuous Integration: Jenkins (self hosted)
Educating ourselves: Safari, Mixergy
Code: Groovy
Web framework: Grails
IDE: Eclipse