How can I get a list of all associations from my model

Hi All

I have a model defined as follows:

class a< ActiveRecord::Base
  has_many :a_b_mappings
  has_many :bs, :through => :a_b_mappings, :uniq => true

  has_many :a_c_mappings
  has_many :cs, :through => :a_c_mappings, :uniq=> true

  has_many :a_d_mappings
  has_many :ds, :through => :a_d_mappings, :uniq => true

...

end

I'm trying to find a class method that will enumerate all the classes
(:bs,:cs,:ds,...) being associated from class a.
I'm at a loss as to what hooks ActiveRecord provides that would enable
me to do that.

Thanks much
Kretch