Lighting Effects

Cold / Warm

You can add to the feeling of coldness or warmth by using additional filters or doubling up on gels. Very blue means very cold, very red/orange means very hot.

Moonlight (or any night-time light)

This is an old standard technique which has become something of a cliché. You can make daytime seem like night by lowering the exposure slightly and adding a blue filter to the camera. However a convincing illusion may require more effort than this — you don't want any daytime giveaways such as birds flying through shot. You also need to think about any other lighting which should appear in shot, such as house or street lights.

Firelight

To light a person's face as if they were looking at a fire, try this: Point a redhead with orange gel away from the subject at a large reflector which reflects the light back at the subject. Shake the reflector to simulate firelight (remember to add sound effects as well).

Watching TV

To light a person's face as if they were watching TV, shine a blue light at the subject and wave a piece of cloth or paper in front of the light to simulate flickering.

Use "Real" Lights

Some filmmakers prefer to use natural light and "real" light sources. For example, have a look at this scene from Stanley Kubrick's Barry Lyndon, which was apparently filmed using only candlelight (according to en.wikipedia.org/wiki/Barry_Lyndon).