This piece of hardware enables you to connect a number of TWI sensors to your PC via USB. At this moment the board supports one SHT11 and up to 8 DS1621. These sensors can measure temperature (DS1621) and relatvive humidity (SHT11). A PC client is capable of writing the data into a MySQL database. The data can then be visualized with Gnuplot using the plotting tool, providing a multitude of options.
USB sensor board - [Link]