Wikipedia: Oort Cloud
Postulated spherical cloud of comets situated about 50,000 to 100,000 AU from the sun.
Kuiper Belt and the Oort Cloud
Discusses the proposed vast cloud at the outer reaches of the solar system that comets reside in.
Views of the Solar System: The Oort Cloud
Introduction the immense spherical cloud surrounding the planetary system, considered the edge of the Sun's orb of physical, gravitational, or dynamical influence.
Oort Cloud & Sol b?
Briefly discusses Oort Could objects, including comets and brown dwarfs.