PDB Atlas: JenaLib
Jena Library of Biological Macromolecules (JenaLib) is an atlas of the Protein Data Bank (PDB) as well as the Nucleic Acid Database (NAD). JenaLib has many options that build upon the PDB and NAD. A feature that jumped out to me was the ability to generate customized lists. I have been using the PDB to generate customized lists by exporting them into excel followed by various sorting tricks.
The process has some friction.
JenaLib under Entry Lists allows you to create customized lists on a variety of topics:

These can be further refined by a number of factors such as collection method, Ligand/Ion and much more. The list can be outputted as html or a .tsv file. A TVS formatted file can be imported into excel via Edit -> Paste Special -> Unicode Text. If you use this import method then each output will be assigned its own cell.
I could see this being really helpful for those that are involved in the bioinformatic side of macromolecular structures.