Shooting indoors, in the evening, with lamp light is my least favorite lighting situation. I recently was at such a shoot, and I had to decide to use flash or to try to soften things up a bit. Any hard light (light bulbs, sun) can be softened with a diffuser, and the larger the surface area of the diffuser, the softer the light will be. We ended up grabbing a simple white sheet and stapled it to the ceiling, creating a giant diffuser. I used no artificial flash and shot at about 1/50 1.4 for the entire shoot.
This is a good trick to know, if you only have hard light and want soft shadows, find a creative way to diffuse the light!If you notice, there are no hard shadows in the image. This is the result of a large, close light source. (The colors in the full size images are much better!)