Toploader AW 65
Anyway, I digress. For your Nikon, I'd suggest a compact padded case that can be carried comfortably outside your pack. A good example is Lowepro's Toploader 65 AW ($65; www.lowepro.com). It's a weather-resistant padded case specifically designed to carry a compact SLR like the D70 and a short zoom lens. A small accessory pocket holds spare batteries and lens cleaners. The Toploader 65 comes with a shoulder/neck strap, and for $10 more you can add a chest harness. That way you can keep the camera right in front and within easy reach, even while wearing a pack. For a longer zoom than, say, a 35-70mm, you might need a longer version of the Toploader, such as the Toploader 70 AW ($90).
Keep in mind that Nikon makes a case specifically for the D70, called the CF-D70 ($49; www.nikonmall.com). It's a snug-fitting, semi-soft case, so doesn't offer quite the protection of the Toploader, although it's more compact. It'll accommodate the camera and a zoom lens.
Read Outside Online's Gear Blog for an opinionated peek at Mountainsmith's new line of camera packs, perfect for a Yosemite foray or any outdoor expedition.