There are many more databases at NCBI. You will probably want to check the Sequence Read Archive (SRA) database (previously known as Short Read Archive) if you are working with NGS data. The SNP database contains information on single-nucleotide polymorphisms (SNPs), whereas the protein database has protein sequences, and so on. A full list of databases in Entrez is linked in the See also section of this recipe.
Another database that you probably already know about with regard to NCBI is PubMed, which includes a list of scientific and medical citations, abstracts, and even full texts. You can also access it via Biopython. Furthermore, GenBank records often contain links to PubMed. For example, we can perform this on our previous ...