Hans Reich's NMR Resources
A top resource for small molecule NMR spectroscopy, covering both the theory and practice of NMR and spectra interpretation. Includes a a large library of chemical shift values and J-couplings. Excellent for both beginners and NMR veterans. The parent website is also a general chemistry resource.
Spectra Database for Organic Compounds
A fully searchable database of real NMR spectra. You can search by (partial or complete) molecular formula, or by entering observed chemical shifts to find possible matches. Also contains searchable IR, Raman, MS, and EPR data.