I heard of a teacher that had students act as a consultant company. They solved problems that other real companies would need to solve.
Telannia Norfar--a member of this group--offers great examples of using PBL for authentic math projects. Take a look at her wiki for examples of real-world math. As Jim mentioned, she has her students act as consultants to solve problems (she's the CEO of her classroom, which she calls Logic Inc.).
When it comes to science, there are many good models. You might start with the project showcase shared by Science Leadership Academy. I especially like the physics example involving public transportation.
I'll be eager to hear other responses--and you're right, this is a terrific group for sharing ideas!
Yes, I can help, it would be my pleasure.
I'm busy developing several projects in 7th and 8th grade life and physical science classrooms. See the blog and websites for a little more information.
I suggest you check out Edutopia's PBL blogs and community, and see their "Schools that Work" header. For each school, they have suggestions for how to implement the PBL models you like. Often with video clips etc.
We'll be presenting at NSTA's national conference in San Francisco in March. Are you going? I'm happy to talk with you about the joys and challenges of implementing PBL in a very traditional school setting and culture.
I know that a teacher in our district uses this book to create real-world instructional environments where students are involved in firsthand experiences. Might be worth a shot.
Our middle schoolers created on OHpedia (wikipedia like), our school is OH Institute, wiki based on the Florida State Standards. This was a PBL project that they did in the beginning of the semester to cover standards before they drilled deeper into a standard that was more aligned to their interests.