I use the RAM2, altimeter logger. Works like the ZLOG, but have no display. It samples for 9 hours, and every time the receiver is turned off/on it logs a new flight. Can read it all on my computer. Some pics can be seen in my review, but the language might be a problem: http://www.modellflynytt.no/articles.php?articleId=135

In my large sailplanes I use the Picolario. This is a telemetri-system which sends vario-signal, height, battery voltage and glitchwarnings down to a receiver on the ground and to an earpiece I use. This system is about to be upgraded with GPS allowing speed and position to be monitored too. This system is a must for everyone who do aerotowing large gliders searching thermals in hights where it is hard to read thelmal on the aircraft. Typically we reach heights of 4000ft before we have to add spoilers and get lower. The nicest gadget among all available