gOpenMol — standard
molekel — The Linux version is much faster than the Window version.
BioStation Viewer — It can draw non-orthogonal contour plots. written by Java.
XCrySDen — Fermi surfaces, 3D contour plots in the non-orthogonal axises
xmakemol — a successor to xmol
OpenDX — may fail to install.

high performance LAPACK and BLAS by Kazushige Goto (Visiting Scientist, FLAME project, UT-Austin) — faster than ATLAS
Numerical Recipes Software's Books On-Line

Primo PDF — free pdf converter in MS-Windows

input tool for fortran and C
malloc/free checker for C
DIIS method
ATM with imaginary part

Kobayashi's HP — huge collection of links to other researchers
NIST chemistry webbook — database of molecules