Flashlight or a headlamp with extra batteries (and light bulb if not LED). Green cyalume stick or small turtle lights as emergency backup.
Whistle (such as Fox 40 whistle with a lanyard), bear bangers, pencil flare
Matches (waterproof or in plastic bag) or lighter, commercial firestarter and/or a candle.
Hat, toque, gloves, mittens, fleece jacket, gortex jacket, polypro underwear, good quality hiking socks and gortex overpants.
Although a multi-tool is preferred, a good pocketknife with a quality blade will suffice. It may also be worth carrying a small pruning saw for cutting branches when building a shelter or fire.
Large orange plastic bag and thermal tarp.
A water purification stick is useful for natural water sources in case your supply runs dry. Gatorade crystals offer electrolytes and will help keep you hydrated for a prolonged period.
Should include pocket mask; SAM Splint, bulk dressings, protective gloves, bandage, scissors and blister dressings.
Good quality compass with built in declination adjustment and both topographical and interpretive maps; GPS unit as an adjunct to compass and map.
Bring mobile phone with a fully charged battery. It is advisable to keep the phone turned off and stored in a ziplock bag to keep it dry and fully charged. Many people manage to call 911 initially but their phone dies before their location can be relayed. If you have a smartphone, you should also know how to get GPS coordinates to give to search and rescue if you become lost or injured. Depending on the terrain, it may also be worth considering satellite based communications devices.