There are a number of honors during the service which you can assign to family and friends.
Aliyot
*Generally, the family is allowed 4 aliyot (blessings before and after a specific Torah reading). One of the four aliyot will be for your child and there will be three more for family and/or friends.
Ark Openings
*There are generally two Ark openings and closings available to honor friends and family (between one and four people for each.)
Gelilah
*The Gelilah helps to bind and dress the Torah with its cover and ornaments after the completion of the entire Torah reading.
Readings
Ashrei
This prayer can be chanted by the B-Mitzvah student, a younger sibling, cousin or a close friend. (This honor is optional.)
(*Participants for above honors with an asterisk are required to be Jewish.)