Some more of my favorites on YouTube:
King Crocoduck
This guy is as thorough as they come. He can get profoundly technical and it can be hard to follow, but he's an incredible poster, it's worth occasionally getting somewhat lost, it'll all come together.
Baud2Bits
I love this guy. AronRa said Baud2Bits was one of the only YouTubers to which he (Aron) is subscribed.
Logicked
He's much more inclined to be looking for gags, but for the most part I enjoy his shtick. I love what he did to Kent Hovind (more on KH when I discuss those whom I vigorously oppose), he's done an entire KH series which I enjoyed tremendously
Hello, My Name is Kent Hovind
Speaking of looking to getting a few good yucks:
Creationist Cat
However, NOT a fan of (the admittedly lovely) Jaclyn Glenn