Topology

Topology and Geometry
http://www.geometrygames.org/
KnotPlot by Rob Scharein
http://www.cs.ubc.ca/labs/imager/contributions/scharein/KnotPlot.html
TangleSolve
http://bio.math.berkeley.edu/TangleSolve/
CompuTop.org: Computational Topology
http://www.computop.org/
Knots on the Web (Peter Suber)
http://www.earlham.edu/~peters/knotlink.htm
Georgia Topology Conference
http://www.math.uga.edu/~topology/
British Topology
http://www.maths.gla.ac.uk/~ajb/btop.html
Mark Brittenham’s Links to Low-Dimensional Topology
http://www.math.unl.edu/~mbritten/ldt/general.html