In the statistical program R, there are packages that can do that for you.

fNonlinear, tseriesChaos, Also see the R discussion group - 

http://www.inside-r.org/packages/cran/fractal/docs/lyapunov

Thank you James. 

And there is:

- Tisean and

- RTisean

see: http://www.mpipks-dresden.mpg.de/~tisean/Tisean_3.0.1/index.html

But I found that estimating Lyapunov exponents can be difficult if just done "out of the box" (except for the standard textbook cases).

So I am also interested myself to know whether there is something more practical, especially for students.

Thomas