Web Resources:

• Textbooks: The Cell-A Molecular Approach 2nd ed., Molecular Biology of the Cell 4th ed., Molecular Cell Biology 4th ed. 
• Gwen Child's introduction to the structure of the cell nucleus is an excellent source of the most basic information on the cell nucleus. Specific links to regions of particular interest within her site are as follows: The Cell Nucleus Chromosome Structure Nuclear Envelope
• The Nuclear Protein Database contains image-based access to information on nuclear compartments.  It is an excellent resource to learn about different types of chromatin and nuclear bodies. 
• Jeanne Lawrence Laboratory: Splicing Factor Compartments, Cajal Bodies, Barr Bodies (Inactive X chromosomes), PML Nuclear Bodies
• Kimball's Biology Pages include an introduction to histones, nucleosomes, chromatin, nuclear pores, and major nuclear organelles
• Wikipedia cell nucleus page