git (private server)
Alternative: github
Cashboard Alternative: client system
2nd git repo
Alternative: Basecamp
Skype
Alternative: IRC, Campfire
Pivotal Tracker
Jenkins
Errbit
Alternative: Exception Notifier, Airbrake
Scout
Alternative: New Relic
Pingdom (though there are plenty of other good alternatives)
Google Analytics
Alternative: gaug.es
Rails 3.1
Alternative: Sinatra
PostgreSQL 9.x
Alternative: PostgreSQL 8.4
Redis, MongoDB
Slim
Alternative: ERB, HAML
None.
Alternative: Formtastic
Sass
Alternative: CSS, LESS
Zepto
Alternative: jQuery
None, what's built into Rails 3.1 is good enough
320 and Up
Alternative: Twitter Bootstrap
None. Alternative: Cucumber
Test::Unit
Alternative: Rspec
Jasmine
Alternative: Vows
capybara and jasmine-headless-webkit Alternative: capybara-webkit, akephalos, phantom.js with ghostbuster
Mocha, Fabrication, VCR
None
Alternative: Capistrano if not on Heroku
Bundler
Rails 3 Asset Pipeline
Alternative: Jammit
NIH w/ Warden
Alternative: Devise, CanCan, maybe OmniAuth
Carrierwave
Alternative: Paperclip
Hand-rolled code
Heroku
Alternative: RimuHosting, Rackspace
Heroku
Alternative: nginx + Thin
Sendgrid
None
TBD
Braintree with transparent redirect
Alternative: Stripe, Authorize.net direct post