I feel that our band could really have a fuller sound, and do more musically with a second guitarist. The problem is, I can't find one. I've checked Craigslist and a few similar websites already. For those of you that have a rhthym guitarist, or any band member that you had to search for, how did you find them? 

...a good Rhythm player can drive and move the band/music just as much as a solid drummer or bassist and if you have all three of them in the pocket you've got an unstoppable train. Just refer to the Beatles, Stones, Who, Aerosmith and countless other bands
and as far as finding a good rhythm player the usual advice applies....cl, adds in music stores, local jams ect.