How do you make a variable available to all views?

Another stupid question:
I have a variable that gets inserted into the main layout. Now, it would
be silly to go and set it as an instance variable for every single
method, right? But when I try to set it in the application.rb file, say
using "@variable = Variable.find(:first)", it isn't available to any of
my views. I tried putting the extra "@" in front of the instance
variable name to make "@@variable", but that didn't work either. Anybody
know what I'm doing wrong? Should I set it as a constant maybe?

Set it from a filter in your application controller.