After I couldn't find a free "Family Guy" Theme ringtone for my cellphone, I decided to use the ringtone composer on my Samsung R225m to make it myself. It sounds pretty good, if I may say so myself. I used the nokring software to convert it to RTTTL. If you have a Nokia, I guess you can enter the following in as a text message and send it to yourself.
RTTTL for "Family Guy" Theme:
Family Guy Theme:d=4,o=4,b=160:
If you have a Samsung like me, you can download the nokring software, cut and paste the RTTTL above, and it will convert it into musical notes for you to manually enter into your phone.
Here is a webpage with some free ringtones