Many of these sites will be familiar ones. As much as possible, I've put the link directly to the listing of physics lesson plans for each site to save you a little time!
Common Lesson Plan Sites
Teach-nology - a long list of lessons covering multiple grade levels.
Lesson Plans Page - Easily searchable for physics lesson plans at any grade level.
DiscoverySchool.com - a great site for lesson plans, mostly for grades 6-8
Smile Program - lists of physics lesson plans by category: Matter; Mechanics; Fluids; Electricity & Magnetism; Waves, Sounds, & Optics; Miscellaneous
Physics Units
Solids, Liquids and Gases - Created by Rachel Miller
Electricity - Created by Amy Hoppes
Speed and Motion - Created by Jen Felix
Simple Machines - Created by Kris Rogers
Solids, Liquids and Gases - Created by Krishna Synder
Sound - Created by Jael Sylva
Electricity - Created by Andrea Stallsmith
Force and Motion - Created by Angie Beer
Sound - Created by Kristina Berger
Force and Motion - Created by Cara Baumgartner
Magical Magnetism - Created by Jill Wynn
Magnets - Created by Jennifer Shanks
Simple Machines - Created by Kelly Switzer
Sound - Created by Lauren Fine
Simple Machines - Created by Lindsey Lewis