The first song I heard and video I saw from Deadmau5 was Ghosts N Stuff. I thought it was a really catchy and fun video. Of course I especially like the mouse head concept. We went to see one of his set a couple years ago and seeing a big head playing on stage at a club definitely adds a fun atmosphere to the club.
One of the things I find really interesting about him is that he shares his work process online and even though I'm no EDM expert, I find it very motivating because you get to see the amount of work it takes to come up with a good product. I used to leave his live stream playing in the background while I was working on interior design projects at 3-4AM. For some reason it was encouraging to not be the only one working during "odd" hours, trying to get things right. Now I'm more into his coffee run video series on YouTube. It's such a great opportunity to be virtually sitting with them and be able to learn from people who are doing what they are passionate about and are very successful at it. I find it very inspiring and manage to learn a lot from these little clips.