WOW! There are approximately 10 to the 5 billionth science project sites out there, but this one is my absolute current favorite. I have been teaching for 10 years and this is the most comprehensive, not-your-typical-5th-grade-project site. Where to start? How about the
I ran through the wizard myself, pretending to be the 8th grade version of me, and I got a terrific selection of age-appropriate projects. Actually, I think conceptually these are pushing the envelope, but that's exactly why I liked them. They give you topics based on your interests (the survey itself is interesting--2 phases of questions, the second refines searches based on your first set of answers). You can also refine your search after you get your results by increasing or decreasing the difficulty level of the problem being investigated.
I'm going to require my students to complete the wizard...I'll let you know how it goes.
Oh, I forgot to tell you about the other excellent part: The PDF document called "What makes a great science lab notebook?". I also have been teaching about and using notebooks for years, but it is extremely difficult to find actual images taken of professional scientist's notebooks. This guide is written at an appropriate level, and includes pictures that illustrate each example. Phenomenal!