We can't say enough good things about MolMol! All the molecular structures on this site were made with MolMol.
We use NMRPipe for all our off line NMR processing
We use NMRview for viewing NMR spectra, assignments, peak picking, you name it.
Modeller is a nice program for modeling a homologous protein sequence on a known 3D structure.
We use CNS to calculate our NMR structures.
A great resource for all types of information including BLAST searches and PubMed.
The source for molecular structures
BioMagResBank: The "PDB" for NMR structures. It contains chemical shifts and constraints for NMR structures in the PDB as well as
lots of other good stuff.