Software to draw links or knots

I am looking for software that can aid me in drawing knots and links. There are of course (examples) knotplotters all over the web, but they can only draw specific knots.

What I am looking for is the software that for example Selman Akbulut used to draw the pictures in his topology presentations (see for example http://www.math.msu.edu/~akbulut/vita/lec.html). It looks like he is using something (else than obviously a huge amount of caffeine) to draw freehand...

Alas, there is no email address on his homepage so I can ask him personally.

I looked into packages which can draw knots and links directly into LaTeX, but they all seem to be too cumbersome when you draw really complicated links.

Edit: Seems that Akbulut is just using a drawing aid. Probably one of those described in the answers below. Further, he seemed to be somewhat cross with the nomenclature (Kirby diagrams), since he developed something similar one year before Kirby's paper in 1977. So maybe we have to use a more careful phrase. Obviously, I didn't know of some friction going on there, I just think it is a nice way to represent 4-dimensional handlebodies, no matter what you call it...

See Drawing knots using computers for a tutorial and Knot Software for a list of programs (some links are broken but Google can help). KnotPlot seems very nice if you want to get fancy.

If you are into LaTeX, you can use this package to actually get fast results using the powerful TikZ/PGF packages. Or pst-knot package with PSTricks.