Premium, no-limit knives? Chris Reeves, Busse, Benchmade, high-level Spydercos, Microtech, Masters of Defense, Extrema Ratio, Emerson
Mid-price, good quality knives? Becker (Try the Becker Necker BK11...it rocks), all other spydercos, high-level CRKT, Camillus
Good-quality budget knives? Becker (LOL Got my BK11 for 38 bucks + shipping), all other CRKT, Kershaw (w00t! Storm rocks, as does the vapor, chive, and any other SpeedSafe-equipped model), Cold Steel, Buck, Case, Opinel
Please stay away from Smith & Wesson. Extremely poor build quality and heat-treat. Same for new Gerbers. Try a Kershaw Vapor for a non-assisted opening knife that has decent steel and is sharp as hell. Or double your budget, go to Wal-mart and get a Spyderco Native with a scary-sharp blade made of awesome steel - it's one of the best deals out there right now.
Also, Ka-Bar makes great budget knives.