I love THIS thread at KVR-VST. It was started by David Kerzner (aka Squids), who runs Sonic Reality and is a keyboard boffin/programmer who has worked with loads of people. The post is about a group-buy offer for some Mellotron sample CDs. What makes it great is his descriptions of where the sounds came from. He's sampled Joni Mitchell's Mellotron, Tom Waite's Chamberlin, Smashing Pumpkin's Optigan, the Mellotron U2 used on 'Unforgettable Fire' and lots more. The sample collection sounds really interesting, but it's Squids stories that sell them (like the one where he accidentally chats up Brooke Shields). Later on, he posts a mad prog-rock demo which almost makes me want to buy the CDs. For free but 95% less atmospheric Mellotron noises, try Tapeworm.