This data logger project records 6 temperatures (to 0.1 deg C resolution) and 2 relative humidity measurements to a microSD card.It uses a 14M2 and AXE133Y OLED display, plus 08M2s in the temperature and humidity sensor modules.The real time clock can be set by loading a file to the microSD card, as can the logger sample interval (from 1 minute to 23 hours 59 minutes). Up to 16 Gb of data can be logged.
The logger has a small power supply and also a 9V battery for back up during power cuts. The temperature and humidity sensor modules transmit serial data to the logger and are cheap and easy to use - they could drive a serial display directly or send ASCII data to a PC if required.
The logger could easily be reconfigured to measure analogue or other sensors. The storage capacity of the microSD card is large, so the logger code could be modified to sample analogue samples more frequently than the limits imposed in the current version from the slow read time of the DS18B20 sensors.
There is a better description of the logger on the Picaxe forum, here: