I see you have a Pearl.
I downloaded the Color Pearl software from geek and proud
Just click on the "BlackBerry Software" link on the right side of the page, then scrool dwon a bit until you see "Color Pear"
It doesn't change your meypad color but does do it to your trackball. The color choices are Red, Blue, Green, Cyan, Pink, Yellow, and of course, White. It says you can create your own colors with HEX numbers, but it doesn't seem to work well. My trackball is red right now and it rocks!
Tried to go to geeks and proud but would not let me click on blackberry software.
Posted from my CrackBerry at wapforums.crackberry.com
I found it's a lot easier to get the Color Pearl software from them if you download and install itu sing desktop manager. Try that and see if it works better.
There was a post about taking apart the phone and using a piece of colored tape to cover the led's. I have an 8130, so there's no changing the trackball color by software for me.
I used a piece of Letraset Color Film and did the mod in like 15 minutes.
It's not as easy as software, but it also doesn't take up any memory.
I think you can only change the trackball color on the 8100... all others are fixed. I don't know of a single phone that you can change the keypad colors on. All I can change on my phone is the external LED.
You can change the way LED notifies you using this small useful software called LED Notifier.
You can set it to show a red LED when your boss calls or emails, a blue one when your girlfriend sends you a text and green when your favorite newsletter lands in your inbox. You can have a different color LED blinking for a different contact
It works really nice and can do customs ones as well. I do notice however it drains the battery faster using fancier led flashing pattern and getting quite a few notice on a regular basis.