It is well known that for a given transfer function matrix $G(s)$ there exist in general infinitly many matrices $(A,B,C,D)$ such that
$$ G(s) = C(sI - A)^{-1}B + D $$
where $s$ is the complex Laplace variable and $I$ the identity matrix.
Three well known "special" realizations are the controllable canonical form, the observable canonical form and the Jordan canonical form.
Question: Are there other "special" (or: not so well known) realizations than the three mentioned, which are useful/used for different purposes?
Also a list/reference of such realizations would be very interesting.