I use one of these as a mic.
http://www.sweetwater.com/store/detail/E602/
The key to kick drums is placement... minor changes in the direction of the mic will make drastic changes in the sound of the recording. For instance, positioning the mic so that it's inside the kick, but pointing at the shell will produce a boomier sound, but rotating the mic to point more at the beater will give you more of a pointed sound.
Check the specs on your vocal mic though. There probably won't be much low freq response as some of the dedicated kick drum mics.