You can try something other than tea but it won't be kombucha and I have no idea what you'll get or if it will breed mold. So, IOW, drink at your own risk--seriously.
IMO kombucha tastes best when brewed w/ black tea. It will be tart because the SCOBY consumes the sugar and converts it into wonderful vitamins and amino acids.
"Wild Fermentation" by Sandor Katz is a great book if you want to start fermenting other things.
http://www.wildfermentation.com/ There's also books specifically about homemade fermented cider, too.