MrLynnHistory Youtube Channel - in the playlist section, this teacher has created a playlist of videos covering key topics broken down by unit; some videos he created, others videos like CrashCourse, etc. Good source to find a video on a key topic you know you need to understand better www.youtube.com/channel/UC_ktMBk0EOC33BMthLrJf6w
Jeopardy Reviews - I have not looked at a lot of these, but I have looked at the AP Human Geography jeopardy reviews from this same site and they are pretty decent. Some might be student-created, so they are still a good quick review of key concepts, but you must be familiar enough with the content to recognize an incorrect answer (but I haven't noticed any). So, check these out if looking for a fun way to review--who doesn't love Jeopardy?!?!?