Links
- http://www.math.unideb.hu/
 Mathematical Institute, University of Debrecen
- http://www.math.leidenuniv.nl/
 Mathematical Institute, Leiden University
- http://escherdroste.math.leidenuniv.nl/
 Applying mathematics to Escher's Print Gallery
- http://www.numbertheory.org/
 Number Theory Web
- http://front.math.ucdavis.edu/
 Front for the Mathematics Arxiv
- http://listserv.nodak.edu/archives/nmbrthry.html
 Number Theory List
- http://distrowatch.com 
 a very popular site with release news and reviews
- http://www.archlinux.org 
 Arch Linux
- http://frugalware.org 
 Frugalware Linux
- http://www.slackware.com 
 Slackware Linux
- http://www.ubuntulinux.org 
 Ubuntu Linux
- http://freshmeat.net 
 if you look for some software it is a good site to start...
- TeXmacs 
 a wysiwyg free scientific text editor and
 interface for computer algebra systems
- Kile 
 a user friendly TeX/LaTeX editor
