Agreed - I have to mention necroscope86 on YouTube. By far my favorite LP'er. I think he had a snafu with his account that deleted a bunch of videos, but he had some very funny X-COM play throughs. It was more about his commentary and British accent that made it worth watching than the actual games themselves.
Some of my favorite LPs have come from LtMkilla (Dead Space and the ill-fated Bioshock LPs come to mind). His humor probably isn't for everybody (whose is?), but I love his videos.
If we're highlighting great LPs, I'll have to throw in a recommendation for ChipCheezum's LPs of the Metal Gear Solid games. The humour is spot on, and the games themselves are covered in exhaustive detail. His LPs of Mega Man Legends and the Uncharted series are great too.
