A brief explainer on AP classes and why you might consider taking one. 
Student Art Guide is a GREAT source for sketchbook/project/concentration topic ideas.  Make sure and explore the 'Articles' and 'Resources' areas.
Newbury Park High School has TONS of sample student photography portfolios (with scores!)
The Official CollegeBoard AP site.  Dig around and find sample student portfolios with scoring rationales, course overviews, and course info regarding AP 2D Studio Design
This web aggregator combs the internet for interesting stuff.  It's a good place to browse when you're bored or looking for inspiration.
Like Colossal, another aggregator site to explore when you need a hit of inspiration.
Examples provided by CollegeBoard
(literally) Everything is here.  
A massive archive of searchable artworks by pretty much every artist ever.
Interactive visualization of how different camera settings affect overall image... Do you know how changing settings (Shutter speed, aperture, ISO, etc) affect exposure, depth of field, focus, and grain texture?  This site will help you understand those relationships and better control them in your own work.
All kinds of sample portfolios for past years' AP 2D Studio Design students
A collection of past years' students AP 2D work
This link isn't exactly related to AP 2D Studio Design, but it's here as a shout-out to Noelle Bennett and her Learning Haven Students.
Concentration Idea Lists... You know how to Google things.  Have you tried Googling up some ideas for Concentration topics?  There are a lot of examples out there- Here's a good one.  And here's another good one.