From Geoff Peters:
GeoTip is a simple program for your cell phone or Blackberry that will calculate the tip for you at restaurants. It should work on most modern mobile phones that support Java and MIDP 2.0 (such as Nokia Series 40/60, Motorola, Blackberry, etc.) Features: Enter meal amount, tax percent, tip percent, how many people to split the bill with, and an optional extra amount to add on the bill (such as liquor tax). Shows the breakdown of tax and tip amounts, total bill, and how much each person owes. Option allows you to save the tax and tip percent to use next time. This version is the first release on CNET Download.com.