for a standard calls yes there is.
1. Go to your contacts
2. select person
3. hit the menu key
4. select Options
5. set ringtone
For SMS/MMS you will need to get handcent for individual notifications sounds per contact.
Thanks Knyte. Also, where does everybody get their ringtones for the Droid? I got all mine for the Storm from crackberry.com. Do you think they will work or are they Blackberry specific?