New: Notas de Calculo Vectorial
My research interest is about differential geometry and physics (theoretical physics and the like). This is my first degree thesis(spanish)

John Baez's homepage.  Very nice site to learn about everything on mathematics and physics 
www.arxiv.org  
Wikipedia  
www.scholar.google.com  WoW!!, google engine only to find papers! 
http://www.answers.com  Where you can find answers to anything... 
II COLOQUIO DE GEOMETRIA DE LA FMAT My own contribution to our differential geometry meeting at UADY.
Here are some links that could be interesting:
Nice article on quantum entanglement in time:  
thegoddess.org  biophysica.com 
See the extended list for the links above
In spring '04 I attended to a quantum computing seminar. As a result i wrote a little monograph about tensors (in spanish). You can download it here