Torque Pro - Android
Torque Pro ($4.95) is an app based program that allows you to obtain all kinds of data from your engine as well as read & clear DTC (diagnostic trouble codes) via your phone or tablet. This app is gaining traction and some projects are utilizing this app and a 7"-10" tablet as their primary gauges.
Amazing layouts and user configurable
The Torque app has some amazing pre configured layouts but is also completely configurable to your desires. Below are some samples of what can be done. You are only limited by your imagination essentially.
OBDII Bluetooth Interface Module
There are literally hundreds of different OBDII Bluetooth interface modules on the market. Although I haven't tried them all, the BAFX Products 34t5 Bluetooth OBDII Scan Tool for Android Devices seems to work the best on various manufacturers. It can be found on Amazon, Ebay, etc for around $25.00.
Oil Pressure - GM
The Torque Pro app has been out for some years now. Until recently oil pressure (2003+ engines) was not obtainable via the app in that GM did not make the oil pressure a standard OBDII protocol, it was a GM specific PID (specific data stream). So apps like Torque Pro could not read them. Well give the general public time and we will figure it out. I do not take credit for this but it has been floating around the internet for awhile. Below are the steps to manual add the GM Oil Pressure PID to the Torque Pro app.
You'll need to go to: Settings-Manage extra PIDs/Sensors-...-Add custom PID and enter the following values:
Long Name: Oil Pressure PID
Short Name: Oil Pressure
Minimum Value: 0
Maximum Value: 100
OBD Header: Auto