BSP Viewer is a utility designed for mappers for previewing Half-Life 1 .bsp files and technical information about how they are being rendered. This is meant to help mappers find problem areas in their BSP files that need to be optimized.
** very good tool when editing entities inside *.bsp files, good for getting origins & also very important for getting model numbers for brush entities....
Download BSP Viewer v1.5.6 
