Add without addition (or any of the 4 basic arithmetic operators) Problem:
Your goal is to add two input numbers without using any of the following math operators: +,-,*,/.
Additionally, you can't use any built-in functions that are designed to replace those math operators.
Scoring:
Smallest code (in number of bytes) wins.
Update

Most of the programs i've seen either concatenate two arrays containing their numbers, or make first number of a character, append second number characters, then count them all.
Shortest array counter: APL with 8 chars, by Tobia
Shortest array concatenation: Golfscript with 4 chars, by Doorknob
Shortest logarithmic solution: TI-89 Basic with 19 chars, by Quincunx
Integration solution: Mathematica with 45 chars, by Michael Stern
Coolest, in my opinion: bitwise operators in javascript, by dave
Javascript (25)

while(y)x^=y,y=(y&amp;x^y)&lt;&lt;1


This adds two variables x and y, using only bitwise operations, and stores the result in x.  

This works with negative numbers, too.