have you thought about doing someone from the zoo, or wildlife place? or the forestry center, police department, or a fitness fun night? you could even do a parent one for budgeting, cooking or even couponing.
We host a mini session event every year where parents, teachers or people from the community come in for a 30 minute session to teach or share info on their skill or job or talent with our students. Some sessions we have are manicures, scrapbooking, high school althletes teach their sport, etc. We seem to have had the same sessions every year and are looking for new ideas???