ATLAS of Finite Group Representations: Representations of many finite simple groups and related groups such as covering groups and automorphism groups of simple groups. Available by FTP in alternative formats: Meataxe ASCII, Meataxe binary, and GAP.
Character Tables for Chemically Important Point Groups: By Achim Gelessus, Mainz.
Collapsed Adjacency Matrices, Character Tables and Ramanujan Graphs: A database of character tables of endomorphism rings.
Groups of Small Order: A list of isomorphism classes and further information on groups of order up to 30, by John Pedersen, University of South Florida.
Small Even Order Groups: Generators for small even ordered groups from 1 to 1000. Files use gzipped extensions and require downloading.
Test Polynomials for Galois Groups: A table of polynomials for Galois groups over the rational numbers with degree up to 9. The table includes links to additional information for each equation.