Drs. Brian Parkin and Prasanth Gogineni have developed a nifty acid-base calculator for the iPhone. Acid Plus from Free Radical Software 
quickly analyzes complex acid-base problems, allowing you to then tilt the iPhone to see a graph with an arrow pointing to the suspected disorder.
Features of Acid Plus from the product page:
Fast, accurate input using the dial Primary calculations including compensations and anion gap with delta delta Ability to discern complex acid/base problems with secondary disorders Detailed views listing common causes of the primary acid-base disorder Colorful graph activated by turning the device right or left Real-time arrow pointing to the correct disorder on the graph Works on both iPhone and iPod touch
Acid Plus product page…
Link to Acid Plus at iTunes…