I would suggest you take a look at some people have made on Craftster, (there might be a tutorial there, I can't remember now) and Etsy too. Here are some really innovative ones I found on Etsy--in case you decide to buy
http://www.etsy.com/view_listing.php?listing_id=11655322 http://www.etsy.com/view_listing.php?listing_id=11320524You also might be able to make your own without a pattern. Use D-rings or clips for adjustable closure.
I found a pattern on Etsy, just in case you do other crafts besides sewing, here it is.
http://www.etsy.com/view_listing.php?listing_id=11114448Also try Lazygirl designs, there is a fanny pack pattern towards the middle here. (scroll down)
http://www.lazygirldesigns.com/bags.phpps...I apologize if the link to another crafting site isnt allowed...please let me know and I will remove it!