I do have a small fanny pack that I got on clearance from REI last year. It has 2 16oz bottles that flank a very small, triangular shaped pocket. It carries: altoid tin PSK, heat sheet, AMK 0.3 FAK, and usually a LM on the belt. There's just enough room to cram in my digital camera and a power bar if I really over load it.
In other words, just the bare essentials, and tops out at what... 5 lbs max?
Otherwise, it's a daypack, which is usually too big for a little extra gear.
http://www.rei.com/product/762546