I use the Qstarz Travel Recorder BT -Q1000 in an earlier version for two years. He is really small.
More than 30 hours battery power and a very good chipset sensitivity.
But you can get smaler recorder, too.
Look at this site.
www.qstarz.com
Does anyone know a good little datalogger for my Run Gps. I have a BIG old HTC phone, in the winter is not to bad carring it with me. But summer I rather have a relatively small and have little light. Has anyone a good idea, not to expensive?