I've recently started my personal wiki to organize my notes and thoughts. I use the wiki program instiki which I believe is the same as the n-lab uses. Instiki can upload svg's. I want to be able to create nice looking pictures of some (not to complicated) geometric objects, e.g. knots, pair of pants, etc. My question is twofold.
Do people draw these things using svg format? For example people who do diagram algebra, do you use svg format?
If so, what are some good free/open source programs for creating these pictures?