Minecraft has a bunch of great Lets Play-ers. If nothing else, they've prompted me to buy /more/ games (like Vessel) because I see a video of someone starting a play-through and it's like a sneak peek into a game that may not offer free trials.

Also - slightly off topic - I can't tell you how many times a game has lost a sale because they didn't have some sort of free trial I could play to see if it was worth my money.