Maybe many of you haven't seen before, the part on the image below. It is a flexible ZNAP axle (x334c01) with 26L length (2L and 5L, usable at the ends).
It is similar to every other TECHNIC axle (rigid or soft), but with the characteristic to be strong and simultaneously flexible. It is made of steal and has a thin transparent plastic cover.
This part appeared at just two ZNAP sets in '98, so it turned already to be a part not easy to find.
If you don't need to apply to much load or torque, this could be an elegant solution also for TECHNIC, to transmit rotational movement between not aligned joints, either in parallel axles or not parallel but also not intercepting axles.
Unfortunately, LEGO just made one length (26L) of these, despite too short lengths may be not feasible at least with an identical construction.
Despite some doubt this could be a reliable and strong driving method, Jennifer Clark made some experiments, which claims to be quite successful and described them on this page (bottom section) at her 'LEGO Construction Site' already referred before at TBs .
The principle could be also applied to transmit rotational movement in a flexible and compact manner, for constructions like the existing boom and jib on the new 2008 Excavator (8294). This again, if not too much torque is required.
Parts like these, could constitute a solution to deliver torque into the Linear Actuators, without using sequences of rigid axles and Universal Joints, where the path to install those might be not easily available.
The alternative use of soft axles would just work for very low torque applications, because both ends will slide when inserted at parts like axle joiners (either + or x hole).