the only one that comes to mind is the Arc'teryx Arrakis which comes in a 50L or 65L (there might be more sizes, not sure). Also, I'm not sure if you don't want to BUY a rain cover or just don't want to USE one... if it's buy, look into packs that have rain covers included. Aside from those two options, mountaineering/specialized winter and alpine packs would be your best bet. They won't be water proof but they'll be very water resistant. My BD Speed 30 repels water very nicely and so does my Mountain Hardwear Dirretissima. They keep my gear dry in all but long, exposed downpours.