Remember: with has_many, use:
Really useful information about ActiveRecord errors in Rails.
Option click the green button.
I had good results using Gliffy…
Online stopwatch (via Lifehacker)
Absolutely critical hex color picker for Mac web development, along with an Applescript application that says (sorry, forgot the source of this):
Weirdest syntax ever:
Gets all name elements of the contacts element, regardless of how deep in the hierarchy they occur.