iPod Ipod Lecture Recording?

I want to record my lectures on my ipod. I've tried the extrememac mic setup, and it works well for recording voice memo's, but it doesn't have the strength to record my lectures. I'm thinking the best way to do it is to buy a seperate mic, and use the 3.5mm plug on the xtrememac adapter, but I have no idea what mic. anyone have any ideas? I'd buy another adapter, if it have been used with good success. thanks for your help! It would be used with a video ipod, although I could use my iphone, or nano, if a better product existed.