if you want something reeeally nice go for Briggsie advice…but if you are just doing it for yourself even a built-in mic of a laptop setup correctly can work well.
I use this http://www.amazon.com/Samson-C03U-USB-Condenser-Microphone/dp/B000QDF3G2/ref=sr_1_1?s=musical-instruments&ie=UTF8&qid=1349566502&sr=1-1&keywords=samson+c03u because it`s usb, and record with the logitech software (because it also record a video), otherwise I use audacity
But I really didn`t needed something so powerful just for recording myself, I just happen to have it.
I can send you some audio piece if you are really interested.
Or you can get a good webcam with mic if you also want to record yourself 🙂