You can use DashCommand on an Iphone or Ipad and an OBD2 blu-tooth or wifi connector.
Which has custom dash boards +can make custom gauge packs of your own design, fault read and reset ECU, + run various performance figures/live data + logging.
There is also a PC version to download and view your logs with/replay your data.
Can show you it in operation at next meet
The correct OBD2 monitor will also work with apps like Harrys Laptimer and 1 or 2 others.
I use GoPoint BT1 blu-tooth adaptor + both the above apps, on a fairly regular bases, you can get slightly quicker wifi units but they use more battery power (not an issue if your connected via power)
You can also connect more accurate GPS tracking units to your phone