Links

Category A

The Mathematics Genealogy Project : Find someone's advisors.

The Integrator : Calculate indefinite integral.

Matrix Reference Manual

Category B

AT&T Yahoo High Speed Internet Speed Test : Measure your network speed.

Category C

Documents(DOC,PPT,...) -> PDF : Free PDF converter

TeXnicCenter : Free LaTeX editor

OLETeX : Any Window Object(Visio,...) -> EPS(vector graphic)