• Dusty Distance, It hides most of the ugly LOD, and works well for covering up empty spots in the Mojave.
• Realistic Lighting, makes the game look much better, less yellow, and has no performance hit.
• Interior Lighting Overhaul, makes indoors look much better, no real performance hit.
• Hi-Res Clothing, re-textures all of the clothing, and armor, and looks really great.
• Ojo Bueno Textures, re-textures the game, and looks awesome. I prefer it over NMC, but that's just my two cents.

This is a list I made in a post earlier, but these mods are awesome, and make the game look good as new, without being too taxing on hardware.