A friend spotted these that I thought were interesting. Wireless dongle in the OBDI port combined with an Android tablet or phone gives you all sorts of interesting gauges for the car. Might be a bit "fast and furious" rice burner stuff but nice to measure torque, HP etc...
https://market.android.com/details?...=W251bGwsMSwyLDIwNiwib3JnLnByb3dsLnRvcnF1ZSJd
http://www.ebay.co.uk/sch/i.html?_n...=elm527&_osacat=0&_trksid=p3286.c0.m270.l1313
https://market.android.com/details?...=W251bGwsMSwyLDIwNiwib3JnLnByb3dsLnRvcnF1ZSJd
http://www.ebay.co.uk/sch/i.html?_n...=elm527&_osacat=0&_trksid=p3286.c0.m270.l1313