A neon effect might be handy for your night time renderings to simulate signage and lighting.

This tutorial on Vray Elite uses the native V-Ray light material (VRayLightMt) as an illumination source.

This downloadable video tutorial uses a self illuminated standard material from max with a V-ray material wrapper (VRayMtlWrapper). Get it here at intrisia.net

You might as well want to try some of these materials from vraymaterials.de:green neon, Bubbleing Neon, neon ultra, Neon blue