On every phone I've had I've used custom ringtones for each person in my family. That way I can know who's calling just by what song is playing. There are times, however, when I have my Blackberry muted, because I'm in an appointment or on my land line phone.
That's where a program like PhonePix: Photo Caller ID comes in handy. The program comes with both a Blackberry component and a Windows component. You can associate a photo and a ringtone with each of your family and friends.
In testing it out I connected my Blackberry to my PC with the USB cable and I was ready to start sending files to my smartphone. I like the fact that I could manipulate the length of sound files so that they took up less space on my phone. The program supports MP3, WAV, and MIDI song formats. When you're ready you just upload your ringtones to your phone. With the desktop software you can work with the images that you'll use to identify callers. The program comes with some default images in case you have callers that you don't have pictures for.
You can rotate images, zoom in, and see each image as it will appear on your device. Slick. Then when you get a call you get a picture of the person and their own special ringtone. I found the program to be very easy-to-use and intuitive, perfect for both new and experienced users.
There's a list of supported Blackberry devices on the company Web site. So, if you'd like to know exactly who's calling your phone, take a good look at PhonePix: Photo Caller ID.
I recommend it.