When the Macintosh first shipped, it had a 72 pixel per inch screen, and a 16x16 pixel pointer. Today, with Apple's 23 and 30 inch displays, we have a much higher pixel per inch count, but the exact same 16x16 pointer. One of the new features of Tiger is the ability to scale up the pointer for those people who have a hard time finding it. I find it's also quite useful if your Mac is hooked up to a TV, or if you have an absurdly high DPI count. Simply scale up the pointer, and you can find it anywhere on the screen. Be warned, the results are a little ugly.
To access this new feature, open System Preferences, then open the Universal Access pane, and click on the Mouse [& Trackpad] tab.
At the bottom of the tab is a slider that adjusts the size of the pointer. I've found that doubling the size (32x32) works best. Move the slider just to the right of the second hash mark; the right diagonal edge of the pointer looks squashed otherwise.

